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[PATCH V4] clk: bcm: Add driver for BCM53573 ILP clock

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  [PATCH V4] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-08-23 08:30 +0200
    [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-08-23 08:30 +0200
      Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Rob Herring <robh@kernel.org> - 2016-08-23 22:20 +0200
        Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-08-25 14:50 +0200
          Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Rob Herring <robh@kernel.org> - 2016-08-31 18:20 +0200
            Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-09-05 14:20 +0200
      Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Stephen Boyd <sboyd@codeaurora.org> - 2016-08-24 11:00 +0200
        Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-08-25 15:50 +0200
          Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Stephen Boyd <sboyd@codeaurora.org> - 2016-08-25 22:00 +0200
        Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-08-25 16:20 +0200
          Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock Stephen Boyd <sboyd@codeaurora.org> - 2016-08-25 22:00 +0200
      [PATCH V6] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-08-26 14:30 +0200
        [PATCH V7] clk: bcm: Add driver for BCM53573 ILP clock Rafał Miłecki <zajec5@gmail.com> - 2016-09-05 16:40 +0200

#1468314 — [PATCH V4] clk: bcm: Add driver for BCM53573 ILP clock

From: Rafał Miłecki <rafal@milecki.pl>

This clock is present on BCM53573 devices (including BCM47189) that use
Cortex-A7. ILP is a part of PMU (Power Management Unit) and so it should
be defined as one of its subnodes (subdevices). For more details see
Documentation entry.

Unfortunately there isn't a set of registers related to ILP clock only.
We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
"retention*" and "control_ext" regs. This is why this driver maps all
0x1000 B of space.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: Rebase on top of clk-next
    Use ALP as parent clock
    Improve comments
    Switch from ioremap_nocache to ioremap
    Check of_clk_add_provide result for error
V3: Drop #include <linux/moduleh>
    Make ILP DT entry part of PMU
    Describe ILP as subdevice of PMU in Documentation
V4: Use BCM53573 name as suggested by Jon and Ray. It seems "Northstar"
    (even if used in some resources) should be used in relation to
    Cortex-A9 devices only.
---
 .../bindings/clock/brcm,bcm53573-ilp.txt           |  40 ++++++
 drivers/clk/bcm/Makefile                           |   1 +
 drivers/clk/bcm/clk-bcm53573-ilp.c                 | 146 +++++++++++++++++++++
 3 files changed, 187 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
 create mode 100644 drivers/clk/bcm/clk-bcm53573-ilp.c

diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
new file mode 100644
index 0000000..73f7d2b
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
@@ -0,0 +1,40 @@
+Broadcom BCM53573 ILP clock
+===========================
+
+This binding uses the common clock binding:
+    Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+This binding is used for ILP clock (sometimes referred as "slow clock")
+on Broadcom BCM53573 devices using Cortex-A7 CPU.
+
+This clock is part of PMU (Power Management Unit), a Broadcom's device
+handing power-related aspects. Please note PMU contains more subdevices,
+ILP is only one of them.
+
+ILP's rate has to be calculated on runtime and it depends on ALP clock
+which has to be referenced.
+
+Required properties:
+- compatible: "brcm,ns-ilp"
+- reg: iomem address range of PMU (Power Management Unit)
+- reg-names: "pmu", the only needed & supported reg right now
+- clocks: has to reference an ALP clock
+- #clock-cells: should be <0>
+
+Example:
+
+pmu@18012000 {
+	compatible = "simple-bus";
+	ranges = <0x00000000 0x18012000 0x00001000>;
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	ilp: ilp@0 {
+		compatible = "brcm,ns-ilp";
+		reg = <0 0x1000>;
+		reg-names = "pmu";
+		clocks = <&alp>;
+		#clock-cells = <0>;
+		clock-output-names = "ilp";
+	};
+};
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index 1d79bd2..4b8c56d 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC)	+= clk-ns2.o
 obj-$(CONFIG_ARCH_BCM_CYGNUS)	+= clk-cygnus.o
 obj-$(CONFIG_ARCH_BCM_NSP)	+= clk-nsp.o
 obj-$(CONFIG_ARCH_BCM_5301X)	+= clk-nsp.o
+obj-$(CONFIG_ARCH_BCM_53573)	+= clk-bcm53573-ilp.o
diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c
new file mode 100644
index 0000000..53b4a23
--- /dev/null
+++ b/drivers/clk/bcm/clk-bcm53573-ilp.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+#define PMU_XTAL_FREQ_RATIO			0x66c
+#define  XTAL_ALP_PER_4ILP			0x00001fff
+#define  XTAL_CTL_EN				0x80000000
+#define PMU_SLOW_CLK_PERIOD			0x6dc
+
+struct ns_ilp {
+	struct clk *clk;
+	struct clk_hw hw;
+	void __iomem *pmu;
+};
+
+static int ns_ilp_enable(struct clk_hw *hw)
+{
+	struct ns_ilp *ilp = container_of(hw, struct ns_ilp, hw);
+
+	writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
+	writel(0x10000, ilp->pmu + 0x674);
+
+	return 0;
+}
+
+static unsigned long ns_ilp_recalc_rate(struct clk_hw *hw,
+					unsigned long parent_rate)
+{
+	struct ns_ilp *ilp = container_of(hw, struct ns_ilp, hw);
+	void __iomem *pmu = ilp->pmu;
+	u32 last_val, cur_val;
+	u32 sum = 0, num = 0, loop_num = 0;
+	u32 avg;
+
+	/* Enable measurement */
+	writel(XTAL_CTL_EN, pmu + PMU_XTAL_FREQ_RATIO);
+
+	/* Read initial value */
+	last_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+	/*
+	 * At minimum we should loop for a bit to let hardware do the
+	 * measurement. This isn't very accurate however, so for a better
+	 * precision lets try getting 20 different values for and use average.
+	 */
+	while (num < 20) {
+		cur_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+		if (cur_val != last_val) {
+			/* Got different value, use it */
+			sum += cur_val;
+			num++;
+			loop_num = 0;
+			last_val = cur_val;
+		} else if (++loop_num > 5000) {
+			/* Same value over and over, give up */
+			sum += cur_val;
+			num++;
+			break;
+		}
+	}
+
+	/* Disable measurement to save power */
+	writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
+
+	avg = sum / num;
+
+	return parent_rate * 4 / avg;
+}
+
+static const struct clk_ops ns_ilp_clk_ops = {
+	.enable = ns_ilp_enable,
+	.recalc_rate = ns_ilp_recalc_rate,
+};
+
+static void ns_ilp_init(struct device_node *np)
+{
+	struct ns_ilp *ilp;
+	struct resource res;
+	struct clk_init_data init = { 0 };
+	const char *parent_name;
+	int index;
+	int err;
+
+	ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
+	if (!ilp)
+		return;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+	if (!parent_name) {
+		err = -ENOENT;
+		goto err_free_ilp;
+	}
+
+	/* TODO: This looks generic, try making it OF helper. */
+	index = of_property_match_string(np, "reg-names", "pmu");
+	if (index < 0) {
+		err = index;
+		goto err_free_ilp;
+	}
+	err = of_address_to_resource(np, index, &res);
+	if (err)
+		goto err_free_ilp;
+	ilp->pmu = ioremap(res.start, resource_size(&res));
+	if (IS_ERR(ilp->pmu)) {
+		err = PTR_ERR(ilp->pmu);
+		goto err_free_ilp;
+	}
+
+	init.name = np->name;
+	init.ops = &ns_ilp_clk_ops;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	ilp->hw.init = &init;
+	ilp->clk = clk_register(NULL, &ilp->hw);
+	if (WARN_ON(IS_ERR(ilp->clk)))
+		goto err_unmap_pmu;
+
+	err = of_clk_add_provider(np, of_clk_src_simple_get, ilp->clk);
+	if (err)
+		goto err_clk_unregister;
+
+	return;
+
+err_clk_unregister:
+	clk_unregister(ilp->clk);
+err_unmap_pmu:
+	iounmap(ilp->pmu);
+err_free_ilp:
+	kfree(ilp);
+	pr_err("Failed to init ILP clock: %d\n", err);
+}
+CLK_OF_DECLARE(ns_ilp_clk, "brcm,ns-ilp", ns_ilp_init);
-- 
2.9.3

[toc] | [next] | [standalone]

#1468317 — [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

From: Rafał Miłecki <rafal@milecki.pl>

This clock is present on BCM53573 devices (including BCM47189) that use
Cortex-A7. ILP is a part of PMU (Power Management Unit) and so it should
be defined as one of its subnodes (subdevices). For more details see
Documentation entry.

Unfortunately there isn't a set of registers related to ILP clock only.
We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
"retention*" and "control_ext" regs. This is why this driver maps all
0x1000 B of space.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: Rebase on top of clk-next
    Use ALP as parent clock
    Improve comments
    Switch from ioremap_nocache to ioremap
    Check of_clk_add_provide result for error
V3: Drop #include <linux/moduleh>
    Make ILP DT entry part of PMU
    Describe ILP as subdevice of PMU in Documentation
V4: Use BCM53573 name as suggested by Jon and Ray. It seems "Northstar"
    (even if used in some resources) should be used in relation to
    Cortex-A9 devices only.
V5: Rename remaining "ns" references to "bcm53573", sorry, I sent V4 too
    early.
---
 .../bindings/clock/brcm,bcm53573-ilp.txt           |  40 ++++++
 drivers/clk/bcm/Makefile                           |   1 +
 drivers/clk/bcm/clk-bcm53573-ilp.c                 | 146 +++++++++++++++++++++
 3 files changed, 187 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
 create mode 100644 drivers/clk/bcm/clk-bcm53573-ilp.c

diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
new file mode 100644
index 0000000..5ab3107
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
@@ -0,0 +1,40 @@
+Broadcom BCM53573 ILP clock
+===========================
+
+This binding uses the common clock binding:
+    Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+This binding is used for ILP clock (sometimes referred as "slow clock")
+on Broadcom BCM53573 devices using Cortex-A7 CPU.
+
+This clock is part of PMU (Power Management Unit), a Broadcom's device
+handing power-related aspects. Please note PMU contains more subdevices,
+ILP is only one of them.
+
+ILP's rate has to be calculated on runtime and it depends on ALP clock
+which has to be referenced.
+
+Required properties:
+- compatible: "brcm,bcm53573-ilp"
+- reg: iomem address range of PMU (Power Management Unit)
+- reg-names: "pmu", the only needed & supported reg right now
+- clocks: has to reference an ALP clock
+- #clock-cells: should be <0>
+
+Example:
+
+pmu@18012000 {
+	compatible = "simple-bus";
+	ranges = <0x00000000 0x18012000 0x00001000>;
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	ilp: ilp@0 {
+		compatible = "brcm,bcm53573-ilp";
+		reg = <0 0x1000>;
+		reg-names = "pmu";
+		clocks = <&alp>;
+		#clock-cells = <0>;
+		clock-output-names = "ilp";
+	};
+};
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index 1d79bd2..4b8c56d 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC)	+= clk-ns2.o
 obj-$(CONFIG_ARCH_BCM_CYGNUS)	+= clk-cygnus.o
 obj-$(CONFIG_ARCH_BCM_NSP)	+= clk-nsp.o
 obj-$(CONFIG_ARCH_BCM_5301X)	+= clk-nsp.o
+obj-$(CONFIG_ARCH_BCM_53573)	+= clk-bcm53573-ilp.o
diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c
new file mode 100644
index 0000000..b7ac0eb
--- /dev/null
+++ b/drivers/clk/bcm/clk-bcm53573-ilp.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+#define PMU_XTAL_FREQ_RATIO			0x66c
+#define  XTAL_ALP_PER_4ILP			0x00001fff
+#define  XTAL_CTL_EN				0x80000000
+#define PMU_SLOW_CLK_PERIOD			0x6dc
+
+struct bcm53573_ilp {
+	struct clk *clk;
+	struct clk_hw hw;
+	void __iomem *pmu;
+};
+
+static int bcm53573_ilp_enable(struct clk_hw *hw)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+
+	writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
+	writel(0x10000, ilp->pmu + 0x674);
+
+	return 0;
+}
+
+static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
+					      unsigned long parent_rate)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+	void __iomem *pmu = ilp->pmu;
+	u32 last_val, cur_val;
+	u32 sum = 0, num = 0, loop_num = 0;
+	u32 avg;
+
+	/* Enable measurement */
+	writel(XTAL_CTL_EN, pmu + PMU_XTAL_FREQ_RATIO);
+
+	/* Read initial value */
+	last_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+	/*
+	 * At minimum we should loop for a bit to let hardware do the
+	 * measurement. This isn't very accurate however, so for a better
+	 * precision lets try getting 20 different values for and use average.
+	 */
+	while (num < 20) {
+		cur_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+		if (cur_val != last_val) {
+			/* Got different value, use it */
+			sum += cur_val;
+			num++;
+			loop_num = 0;
+			last_val = cur_val;
+		} else if (++loop_num > 5000) {
+			/* Same value over and over, give up */
+			sum += cur_val;
+			num++;
+			break;
+		}
+	}
+
+	/* Disable measurement to save power */
+	writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
+
+	avg = sum / num;
+
+	return parent_rate * 4 / avg;
+}
+
+static const struct clk_ops bcm53573_ilp_clk_ops = {
+	.enable = bcm53573_ilp_enable,
+	.recalc_rate = bcm53573_ilp_recalc_rate,
+};
+
+static void bcm53573_ilp_init(struct device_node *np)
+{
+	struct bcm53573_ilp *ilp;
+	struct resource res;
+	struct clk_init_data init = { 0 };
+	const char *parent_name;
+	int index;
+	int err;
+
+	ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
+	if (!ilp)
+		return;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+	if (!parent_name) {
+		err = -ENOENT;
+		goto err_free_ilp;
+	}
+
+	/* TODO: This looks generic, try making it OF helper. */
+	index = of_property_match_string(np, "reg-names", "pmu");
+	if (index < 0) {
+		err = index;
+		goto err_free_ilp;
+	}
+	err = of_address_to_resource(np, index, &res);
+	if (err)
+		goto err_free_ilp;
+	ilp->pmu = ioremap(res.start, resource_size(&res));
+	if (IS_ERR(ilp->pmu)) {
+		err = PTR_ERR(ilp->pmu);
+		goto err_free_ilp;
+	}
+
+	init.name = np->name;
+	init.ops = &bcm53573_ilp_clk_ops;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	ilp->hw.init = &init;
+	ilp->clk = clk_register(NULL, &ilp->hw);
+	if (WARN_ON(IS_ERR(ilp->clk)))
+		goto err_unmap_pmu;
+
+	err = of_clk_add_provider(np, of_clk_src_simple_get, ilp->clk);
+	if (err)
+		goto err_clk_unregister;
+
+	return;
+
+err_clk_unregister:
+	clk_unregister(ilp->clk);
+err_unmap_pmu:
+	iounmap(ilp->pmu);
+err_free_ilp:
+	kfree(ilp);
+	pr_err("Failed to init ILP clock: %d\n", err);
+}
+CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);
-- 
2.9.3

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#1468817 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On Tue, Aug 23, 2016 at 08:25:59AM +0200, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> This clock is present on BCM53573 devices (including BCM47189) that use
> Cortex-A7. ILP is a part of PMU (Power Management Unit) and so it should
> be defined as one of its subnodes (subdevices). For more details see
> Documentation entry.
> 
> Unfortunately there isn't a set of registers related to ILP clock only.
> We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
> "retention*" and "control_ext" regs. This is why this driver maps all
> 0x1000 B of space.

Then describe the block as a syscon which has several functions of 
which clocks are one.

> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
> V2: Rebase on top of clk-next
>     Use ALP as parent clock
>     Improve comments
>     Switch from ioremap_nocache to ioremap
>     Check of_clk_add_provide result for error
> V3: Drop #include <linux/moduleh>
>     Make ILP DT entry part of PMU
>     Describe ILP as subdevice of PMU in Documentation
> V4: Use BCM53573 name as suggested by Jon and Ray. It seems "Northstar"
>     (even if used in some resources) should be used in relation to
>     Cortex-A9 devices only.
> V5: Rename remaining "ns" references to "bcm53573", sorry, I sent V4 too
>     early.
> ---
>  .../bindings/clock/brcm,bcm53573-ilp.txt           |  40 ++++++

Acked-by: Rob Herring <robh@kernel.org>

>  drivers/clk/bcm/Makefile                           |   1 +
>  drivers/clk/bcm/clk-bcm53573-ilp.c                 | 146 +++++++++++++++++++++
>  3 files changed, 187 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
>  create mode 100644 drivers/clk/bcm/clk-bcm53573-ilp.c
> 
> diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
> new file mode 100644
> index 0000000..5ab3107
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
> @@ -0,0 +1,40 @@
> +Broadcom BCM53573 ILP clock
> +===========================
> +
> +This binding uses the common clock binding:
> +    Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +This binding is used for ILP clock (sometimes referred as "slow clock")
> +on Broadcom BCM53573 devices using Cortex-A7 CPU.
> +
> +This clock is part of PMU (Power Management Unit), a Broadcom's device
> +handing power-related aspects. Please note PMU contains more subdevices,
> +ILP is only one of them.
> +
> +ILP's rate has to be calculated on runtime and it depends on ALP clock
> +which has to be referenced.
> +
> +Required properties:
> +- compatible: "brcm,bcm53573-ilp"
> +- reg: iomem address range of PMU (Power Management Unit)
> +- reg-names: "pmu", the only needed & supported reg right now

right now? Please describe all of the h/w. You don't get to change it 
later.

Rob

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#1470121 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On 23 August 2016 at 21:55, Rob Herring <robh@kernel.org> wrote:
> On Tue, Aug 23, 2016 at 08:25:59AM +0200, Rafał Miłecki wrote:
>> From: Rafał Miłecki <rafal@milecki.pl>
>>
>> This clock is present on BCM53573 devices (including BCM47189) that use
>> Cortex-A7. ILP is a part of PMU (Power Management Unit) and so it should
>> be defined as one of its subnodes (subdevices). For more details see
>> Documentation entry.
>>
>> Unfortunately there isn't a set of registers related to ILP clock only.
>> We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
>> "retention*" and "control_ext" regs. This is why this driver maps all
>> 0x1000 B of space.
>
> Then describe the block as a syscon which has several functions of
> which clocks are one.

This isn't clear to me, sorry, could you describe it? Would you like
me to update commit message or documentation? Is code fine as is?

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#1473646 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On Thu, Aug 25, 2016 at 02:42:52PM +0200, Rafał Miłecki wrote:
> On 23 August 2016 at 21:55, Rob Herring <robh@kernel.org> wrote:
> > On Tue, Aug 23, 2016 at 08:25:59AM +0200, Rafał Miłecki wrote:
> >> From: Rafał Miłecki <rafal@milecki.pl>
> >>
> >> This clock is present on BCM53573 devices (including BCM47189) that use
> >> Cortex-A7. ILP is a part of PMU (Power Management Unit) and so it should
> >> be defined as one of its subnodes (subdevices). For more details see
> >> Documentation entry.
> >>
> >> Unfortunately there isn't a set of registers related to ILP clock only.
> >> We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
> >> "retention*" and "control_ext" regs. This is why this driver maps all
> >> 0x1000 B of space.
> >
> > Then describe the block as a syscon which has several functions of
> > which clocks are one.
> 
> This isn't clear to me, sorry, could you describe it? Would you like
> me to update commit message or documentation? Is code fine as is?

Let me put it another way, when you need to use the other registers, how 
do you plan to describe them in DT? We don't really want a node per 
register, nor do I want to get binding docs one by one as you add each 
function. Instead describe the block with all the misc functions as a 
whole. What would you call that block? Still ILP or something else? 

Also, you if you do have multiple drivers all needing to access this 
single block, then that is when you need syscon and regmap.

Rob

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#1476357 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On 31 August 2016 at 18:16, Rob Herring <robh@kernel.org> wrote:
> On Thu, Aug 25, 2016 at 02:42:52PM +0200, Rafał Miłecki wrote:
>> On 23 August 2016 at 21:55, Rob Herring <robh@kernel.org> wrote:
>> > On Tue, Aug 23, 2016 at 08:25:59AM +0200, Rafał Miłecki wrote:
>> >> From: Rafał Miłecki <rafal@milecki.pl>
>> >>
>> >> This clock is present on BCM53573 devices (including BCM47189) that use
>> >> Cortex-A7. ILP is a part of PMU (Power Management Unit) and so it should
>> >> be defined as one of its subnodes (subdevices). For more details see
>> >> Documentation entry.
>> >>
>> >> Unfortunately there isn't a set of registers related to ILP clock only.
>> >> We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
>> >> "retention*" and "control_ext" regs. This is why this driver maps all
>> >> 0x1000 B of space.
>> >
>> > Then describe the block as a syscon which has several functions of
>> > which clocks are one.
>>
>> This isn't clear to me, sorry, could you describe it? Would you like
>> me to update commit message or documentation? Is code fine as is?
>
> Let me put it another way, when you need to use the other registers, how
> do you plan to describe them in DT? We don't really want a node per
> register, nor do I want to get binding docs one by one as you add each
> function. Instead describe the block with all the misc functions as a
> whole. What would you call that block? Still ILP or something else?
>
> Also, you if you do have multiple drivers all needing to access this
> single block, then that is when you need syscon and regmap.

I got this now, thanks for your patience.

One last question: what is preferred register reference:
1) Parent-child (of_get_parent + syscon_node_to_regmap)
or
2) DT property (syscon_regmap_lookup_by_phandle(dt, "foo"))

-- 
Rafał

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#1469234 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On 08/23, Rafał Miłecki wrote:
> diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c
> new file mode 100644
> index 0000000..b7ac0eb
> --- /dev/null
> +++ b/drivers/clk/bcm/clk-bcm53573-ilp.c
> @@ -0,0 +1,146 @@
> +/*
> + * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/clk.h>

Is this include used?

> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/slab.h>
> +
> +#define PMU_XTAL_FREQ_RATIO			0x66c
> +#define  XTAL_ALP_PER_4ILP			0x00001fff
> +#define  XTAL_CTL_EN				0x80000000
> +#define PMU_SLOW_CLK_PERIOD			0x6dc
> +
> +struct bcm53573_ilp {
> +	struct clk *clk;
> +	struct clk_hw hw;
> +	void __iomem *pmu;
> +};
> +
> +static int bcm53573_ilp_enable(struct clk_hw *hw)
> +{
> +	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
> +
> +	writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
> +	writel(0x10000, ilp->pmu + 0x674);

Is there a name for 0x674?
> +
> +	return 0;
> +}
> +
> +static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
> +					      unsigned long parent_rate)
> +{
> +	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
> +	void __iomem *pmu = ilp->pmu;
> +	u32 last_val, cur_val;
> +	u32 sum = 0, num = 0, loop_num = 0;

Should these just be plain ints? Do we care about sizes for these
variables?

> +	u32 avg;

This one too.

> +
> +	/* Enable measurement */
> +	writel(XTAL_CTL_EN, pmu + PMU_XTAL_FREQ_RATIO);
> +
> +	/* Read initial value */
> +	last_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
> +
> +	/*
> +	 * At minimum we should loop for a bit to let hardware do the
> +	 * measurement. This isn't very accurate however, so for a better
> +	 * precision lets try getting 20 different values for and use average.
> +	 */
> +	while (num < 20) {
> +		cur_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
> +
> +		if (cur_val != last_val) {
> +			/* Got different value, use it */
> +			sum += cur_val;
> +			num++;
> +			loop_num = 0;
> +			last_val = cur_val;
> +		} else if (++loop_num > 5000) {
> +			/* Same value over and over, give up */
> +			sum += cur_val;
> +			num++;
> +			break;
> +		}

Should there be a udelay() here? Or we're expected to tight loop
read the hardware? If so we should throw in a cpu_relax() here to
indicate tight loop.

> +	}
> +
> +	/* Disable measurement to save power */
> +	writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
> +
> +	avg = sum / num;
> +
> +	return parent_rate * 4 / avg;
> +}
> +
> +static const struct clk_ops bcm53573_ilp_clk_ops = {
> +	.enable = bcm53573_ilp_enable,

No disable? Or .is_enabled?

> +	.recalc_rate = bcm53573_ilp_recalc_rate,
> +};
> +
> +static void bcm53573_ilp_init(struct device_node *np)
> +{
> +	struct bcm53573_ilp *ilp;
> +	struct resource res;
> +	struct clk_init_data init = { 0 };
> +	const char *parent_name;
> +	int index;
> +	int err;
> +
> +	ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
> +	if (!ilp)
> +		return;
> +
> +	parent_name = of_clk_get_parent_name(np, 0);
> +	if (!parent_name) {
> +		err = -ENOENT;
> +		goto err_free_ilp;
> +	}
> +
> +	/* TODO: This looks generic, try making it OF helper. */
> +	index = of_property_match_string(np, "reg-names", "pmu");
> +	if (index < 0) {
> +		err = index;
> +		goto err_free_ilp;
> +	}
> +	err = of_address_to_resource(np, index, &res);
> +	if (err)
> +		goto err_free_ilp;
> +	ilp->pmu = ioremap(res.start, resource_size(&res));
> +	if (IS_ERR(ilp->pmu)) {
> +		err = PTR_ERR(ilp->pmu);
> +		goto err_free_ilp;
> +	}
> +
> +	init.name = np->name;
> +	init.ops = &bcm53573_ilp_clk_ops;
> +	init.parent_names = &parent_name;
> +	init.num_parents = 1;
> +
> +	ilp->hw.init = &init;
> +	ilp->clk = clk_register(NULL, &ilp->hw);

please use clk_hw_register() and of_clk_add_hw_provider().

> +	if (WARN_ON(IS_ERR(ilp->clk)))
> +		goto err_unmap_pmu;
> +
> +	err = of_clk_add_provider(np, of_clk_src_simple_get, ilp->clk);
> +	if (err)
> +		goto err_clk_unregister;
> +
> +	return;
> +
> +err_clk_unregister:
> +	clk_unregister(ilp->clk);
> +err_unmap_pmu:
> +	iounmap(ilp->pmu);
> +err_free_ilp:
> +	kfree(ilp);
> +	pr_err("Failed to init ILP clock: %d\n", err);
> +}
> +CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);

Can this be a platform driver instead?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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#1470157 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On 24 August 2016 at 10:47, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/23, Rafał Miłecki wrote:
>> diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c
>> new file mode 100644
>> index 0000000..b7ac0eb
>> --- /dev/null
>> +++ b/drivers/clk/bcm/clk-bcm53573-ilp.c
>> @@ -0,0 +1,146 @@
>> +/*
>> + * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#include <linux/clk.h>
>
> Is this include used?

No. Good point.


>> +#include <linux/clk-provider.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/slab.h>
>> +
>> +#define PMU_XTAL_FREQ_RATIO                  0x66c
>> +#define  XTAL_ALP_PER_4ILP                   0x00001fff
>> +#define  XTAL_CTL_EN                         0x80000000
>> +#define PMU_SLOW_CLK_PERIOD                  0x6dc
>> +
>> +struct bcm53573_ilp {
>> +     struct clk *clk;
>> +     struct clk_hw hw;
>> +     void __iomem *pmu;
>> +};
>> +
>> +static int bcm53573_ilp_enable(struct clk_hw *hw)
>> +{
>> +     struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
>> +
>> +     writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
>> +     writel(0x10000, ilp->pmu + 0x674);
>
> Is there a name for 0x674?
>> +
>> +     return 0;
>> +}
>> +
>> +static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
>> +                                           unsigned long parent_rate)
>> +{
>> +     struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
>> +     void __iomem *pmu = ilp->pmu;
>> +     u32 last_val, cur_val;
>> +     u32 sum = 0, num = 0, loop_num = 0;
>
> Should these just be plain ints? Do we care about sizes for these
> variables?
>
>> +     u32 avg;
>
> This one too.

Right.


>> +
>> +     /* Enable measurement */
>> +     writel(XTAL_CTL_EN, pmu + PMU_XTAL_FREQ_RATIO);
>> +
>> +     /* Read initial value */
>> +     last_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
>> +
>> +     /*
>> +      * At minimum we should loop for a bit to let hardware do the
>> +      * measurement. This isn't very accurate however, so for a better
>> +      * precision lets try getting 20 different values for and use average.
>> +      */
>> +     while (num < 20) {
>> +             cur_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
>> +
>> +             if (cur_val != last_val) {
>> +                     /* Got different value, use it */
>> +                     sum += cur_val;
>> +                     num++;
>> +                     loop_num = 0;
>> +                     last_val = cur_val;
>> +             } else if (++loop_num > 5000) {
>> +                     /* Same value over and over, give up */
>> +                     sum += cur_val;
>> +                     num++;
>> +                     break;
>> +             }
>
> Should there be a udelay() here? Or we're expected to tight loop
> read the hardware? If so we should throw in a cpu_relax() here to
> indicate tight loop.
>
>> +     }
>> +
>> +     /* Disable measurement to save power */
>> +     writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
>> +
>> +     avg = sum / num;
>> +
>> +     return parent_rate * 4 / avg;
>> +}
>> +
>> +static const struct clk_ops bcm53573_ilp_clk_ops = {
>> +     .enable = bcm53573_ilp_enable,
>
> No disable? Or .is_enabled?

The beauty of working without datasheets... I'll compare initial reg
state with one after enabling and see if there is sth obvious.


>> +     .recalc_rate = bcm53573_ilp_recalc_rate,
>> +};
>> +
>> +static void bcm53573_ilp_init(struct device_node *np)
>> +{
>> +     struct bcm53573_ilp *ilp;
>> +     struct resource res;
>> +     struct clk_init_data init = { 0 };
>> +     const char *parent_name;
>> +     int index;
>> +     int err;
>> +
>> +     ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
>> +     if (!ilp)
>> +             return;
>> +
>> +     parent_name = of_clk_get_parent_name(np, 0);
>> +     if (!parent_name) {
>> +             err = -ENOENT;
>> +             goto err_free_ilp;
>> +     }
>> +
>> +     /* TODO: This looks generic, try making it OF helper. */
>> +     index = of_property_match_string(np, "reg-names", "pmu");
>> +     if (index < 0) {
>> +             err = index;
>> +             goto err_free_ilp;
>> +     }
>> +     err = of_address_to_resource(np, index, &res);
>> +     if (err)
>> +             goto err_free_ilp;
>> +     ilp->pmu = ioremap(res.start, resource_size(&res));
>> +     if (IS_ERR(ilp->pmu)) {
>> +             err = PTR_ERR(ilp->pmu);
>> +             goto err_free_ilp;
>> +     }
>> +
>> +     init.name = np->name;
>> +     init.ops = &bcm53573_ilp_clk_ops;
>> +     init.parent_names = &parent_name;
>> +     init.num_parents = 1;
>> +
>> +     ilp->hw.init = &init;
>> +     ilp->clk = clk_register(NULL, &ilp->hw);
>
> please use clk_hw_register() and of_clk_add_hw_provider().

I wasn't aware of this API change, thanks.


>> +     if (WARN_ON(IS_ERR(ilp->clk)))
>> +             goto err_unmap_pmu;
>> +
>> +     err = of_clk_add_provider(np, of_clk_src_simple_get, ilp->clk);
>> +     if (err)
>> +             goto err_clk_unregister;
>> +
>> +     return;
>> +
>> +err_clk_unregister:
>> +     clk_unregister(ilp->clk);
>> +err_unmap_pmu:
>> +     iounmap(ilp->pmu);
>> +err_free_ilp:
>> +     kfree(ilp);
>> +     pr_err("Failed to init ILP clock: %d\n", err);
>> +}
>> +CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);
>
> Can this be a platform driver instead?

I guess it can. Should it? It's not clear to me when CLK_OF_DECLARE is
preferred and when it's not.

-- 
Rafał

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#1470369 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On 08/25, Rafał Miłecki wrote:
> On 24 August 2016 at 10:47, Stephen Boyd <sboyd@codeaurora.org> wrote:
> > On 08/23, Rafał Miłecki wrote:
> >> +     }
> >> +
> >> +     /* Disable measurement to save power */
> >> +     writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
> >> +
> >> +     avg = sum / num;
> >> +
> >> +     return parent_rate * 4 / avg;
> >> +}
> >> +
> >> +static const struct clk_ops bcm53573_ilp_clk_ops = {
> >> +     .enable = bcm53573_ilp_enable,
> >
> > No disable? Or .is_enabled?
> 
> The beauty of working without datasheets... I'll compare initial reg
> state with one after enabling and see if there is sth obvious.
> 
> 

Ok.

> >
> > Can this be a platform driver instead?
> 
> I guess it can. Should it? It's not clear to me when CLK_OF_DECLARE is
> preferred and when it's not.

We've been taking an approach of using CLK_OF_DECLARE() for clks
that must be registered for timers and interrupt controllers (as
these things are done before the device model is initialized),
and struct drivers otherwise. If the DT node has a mix of
timer/interrupt controller clks and other clks then
CLK_OF_DECLARE_DRIVER() can be used and then we can still have a
builtin driver.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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#1470176 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On 24 August 2016 at 10:47, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 08/23, Rafał Miłecki wrote:
>> +static int bcm53573_ilp_enable(struct clk_hw *hw)
>> +{
>> +     struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
>> +
>> +     writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
>> +     writel(0x10000, ilp->pmu + 0x674);
>
> Is there a name for 0x674?

No in any sources published by Broadcom. I was experimenting with bit
0x10000 in PMU_SLOW_CLK_PERIOD and 0x10000 in 0x674. Both have to be
set. I was suspecting that maybe one of them is just some trigger and
it can be switched back to 0, but it's not the case. I definitely need
to set both of them to get clock working.

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#1470366 — Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock

On 08/25, Rafał Miłecki wrote:
> On 24 August 2016 at 10:47, Stephen Boyd <sboyd@codeaurora.org> wrote:
> > On 08/23, Rafał Miłecki wrote:
> >> +static int bcm53573_ilp_enable(struct clk_hw *hw)
> >> +{
> >> +     struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
> >> +
> >> +     writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
> >> +     writel(0x10000, ilp->pmu + 0x674);
> >
> > Is there a name for 0x674?
> 
> No in any sources published by Broadcom. I was experimenting with bit
> 0x10000 in PMU_SLOW_CLK_PERIOD and 0x10000 in 0x674. Both have to be
> set. I was suspecting that maybe one of them is just some trigger and
> it can be switched back to 0, but it's not the case. I definitely need
> to set both of them to get clock working.

Ok no worries, raw number is fine.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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#1470677 — [PATCH V6] clk: bcm: Add driver for BCM53573 ILP clock

From: Rafał Miłecki <rafal@milecki.pl>

This clock is present on BCM53573 devices (including BCM47189) that use
Cortex-A7. ILP is a part of PMU (Power Management Unit) and so it should
be defined as one of its subnodes (subdevices). For more details see
Documentation entry.

Unfortunately there isn't a set of registers related to ILP clock only.
We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
"retention*" and "control_ext" regs. This is why this driver maps all
0x1000 B of space.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: Rebase on top of clk-next
    Use ALP as parent clock
    Improve comments
    Switch from ioremap_nocache to ioremap
    Check of_clk_add_provide result for error
V3: Drop #include <linux/moduleh>
    Make ILP DT entry part of PMU
    Describe ILP as subdevice of PMU in Documentation
V4: Use BCM53573 name as suggested by Jon and Ray. It seems "Northstar"
    (even if used in some resources) should be used in relation to
    Cortex-A9 devices only.
V5: Rename remaining "ns" references to "bcm53573", sorry, I sent V4 too
    early.
V6: Drop #include <linux/clk.h>
    Use "int" as type where it matches usage
    Add cpu_relax() in the loop
    Add disable callback
    Use _hw_ functions for registering struct clk_hw (new API)

    Thanks a lot Stephen!
---
 .../bindings/clock/brcm,bcm53573-ilp.txt           |  40 ++++++
 drivers/clk/bcm/Makefile                           |   1 +
 drivers/clk/bcm/clk-bcm53573-ilp.c                 | 157 +++++++++++++++++++++
 3 files changed, 198 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
 create mode 100644 drivers/clk/bcm/clk-bcm53573-ilp.c

diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
new file mode 100644
index 0000000..5ab3107
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
@@ -0,0 +1,40 @@
+Broadcom BCM53573 ILP clock
+===========================
+
+This binding uses the common clock binding:
+    Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+This binding is used for ILP clock (sometimes referred as "slow clock")
+on Broadcom BCM53573 devices using Cortex-A7 CPU.
+
+This clock is part of PMU (Power Management Unit), a Broadcom's device
+handing power-related aspects. Please note PMU contains more subdevices,
+ILP is only one of them.
+
+ILP's rate has to be calculated on runtime and it depends on ALP clock
+which has to be referenced.
+
+Required properties:
+- compatible: "brcm,bcm53573-ilp"
+- reg: iomem address range of PMU (Power Management Unit)
+- reg-names: "pmu", the only needed & supported reg right now
+- clocks: has to reference an ALP clock
+- #clock-cells: should be <0>
+
+Example:
+
+pmu@18012000 {
+	compatible = "simple-bus";
+	ranges = <0x00000000 0x18012000 0x00001000>;
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	ilp: ilp@0 {
+		compatible = "brcm,bcm53573-ilp";
+		reg = <0 0x1000>;
+		reg-names = "pmu";
+		clocks = <&alp>;
+		#clock-cells = <0>;
+		clock-output-names = "ilp";
+	};
+};
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index 1d79bd2..4b8c56d 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC)	+= clk-ns2.o
 obj-$(CONFIG_ARCH_BCM_CYGNUS)	+= clk-cygnus.o
 obj-$(CONFIG_ARCH_BCM_NSP)	+= clk-nsp.o
 obj-$(CONFIG_ARCH_BCM_5301X)	+= clk-nsp.o
+obj-$(CONFIG_ARCH_BCM_53573)	+= clk-bcm53573-ilp.o
diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c
new file mode 100644
index 0000000..faf2b0a
--- /dev/null
+++ b/drivers/clk/bcm/clk-bcm53573-ilp.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+#define PMU_XTAL_FREQ_RATIO			0x66c
+#define  XTAL_ALP_PER_4ILP			0x00001fff
+#define  XTAL_CTL_EN				0x80000000
+#define PMU_SLOW_CLK_PERIOD			0x6dc
+
+struct bcm53573_ilp {
+	struct clk_hw hw;
+	void __iomem *pmu;
+};
+
+static int bcm53573_ilp_enable(struct clk_hw *hw)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+
+	writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
+	writel(0x10000, ilp->pmu + 0x674);
+
+	return 0;
+}
+
+static void bcm53573_ilp_disable(struct clk_hw *hw)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+
+	writel(0, ilp->pmu + PMU_SLOW_CLK_PERIOD);
+	writel(0, ilp->pmu + 0x674);
+}
+
+static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
+					      unsigned long parent_rate)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+	void __iomem *pmu = ilp->pmu;
+	u32 last_val, cur_val;
+	int sum = 0, num = 0, loop_num = 0;
+	int avg;
+
+	/* Enable measurement */
+	writel(XTAL_CTL_EN, pmu + PMU_XTAL_FREQ_RATIO);
+
+	/* Read initial value */
+	last_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+	/*
+	 * At minimum we should loop for a bit to let hardware do the
+	 * measurement. This isn't very accurate however, so for a better
+	 * precision lets try getting 20 different values for and use average.
+	 */
+	while (num < 20) {
+		cur_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+		if (cur_val != last_val) {
+			/* Got different value, use it */
+			sum += cur_val;
+			num++;
+			loop_num = 0;
+			last_val = cur_val;
+		} else if (++loop_num > 5000) {
+			/* Same value over and over, give up */
+			sum += cur_val;
+			num++;
+			break;
+		}
+
+		cpu_relax();
+	}
+
+	/* Disable measurement to save power */
+	writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
+
+	avg = sum / num;
+
+	return parent_rate * 4 / avg;
+}
+
+static const struct clk_ops bcm53573_ilp_clk_ops = {
+	.enable = bcm53573_ilp_enable,
+	.disable = bcm53573_ilp_disable,
+	.recalc_rate = bcm53573_ilp_recalc_rate,
+};
+
+static void bcm53573_ilp_init(struct device_node *np)
+{
+	struct bcm53573_ilp *ilp;
+	struct resource res;
+	struct clk_init_data init = { 0 };
+	const char *parent_name;
+	int index;
+	int err;
+
+	ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
+	if (!ilp)
+		return;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+	if (!parent_name) {
+		err = -ENOENT;
+		goto err_free_ilp;
+	}
+
+	/* TODO: This looks generic, try making it OF helper. */
+	index = of_property_match_string(np, "reg-names", "pmu");
+	if (index < 0) {
+		err = index;
+		goto err_free_ilp;
+	}
+	err = of_address_to_resource(np, index, &res);
+	if (err)
+		goto err_free_ilp;
+	ilp->pmu = ioremap(res.start, resource_size(&res));
+	if (IS_ERR(ilp->pmu)) {
+		err = PTR_ERR(ilp->pmu);
+		goto err_free_ilp;
+	}
+
+	init.name = np->name;
+	init.ops = &bcm53573_ilp_clk_ops;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	ilp->hw.init = &init;
+	err = clk_hw_register(NULL, &ilp->hw);
+	if (err)
+		goto err_unmap_pmu;
+
+	err = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &ilp->hw);
+	if (err)
+		goto err_clk_hw_unregister;
+
+	return;
+
+err_clk_hw_unregister:
+	clk_hw_unregister(&ilp->hw);
+err_unmap_pmu:
+	iounmap(ilp->pmu);
+err_free_ilp:
+	kfree(ilp);
+	pr_err("Failed to init ILP clock: %d\n", err);
+}
+
+/* We need it very early for arch code, before device model gets ready */
+CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);
-- 
2.9.3

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#1476514 — [PATCH V7] clk: bcm: Add driver for BCM53573 ILP clock

From: Rafał Miłecki <rafal@milecki.pl>

This clock is present on BCM53573 devices (including BCM47189) that use
Cortex-A7. ILP is a part of PMU (Power Management Unit) multi-function
device so we use syscon (and regmap) for it.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: Rebase on top of clk-next
    Use ALP as parent clock
    Improve comments
    Switch from ioremap_nocache to ioremap
    Check of_clk_add_provide result for error
V3: Drop #include <linux/moduleh>
    Make ILP DT entry part of PMU
    Describe ILP as subdevice of PMU in Documentation
V4: Use BCM53573 name as suggested by Jon and Ray. It seems "Northstar"
    (even if used in some resources) should be used in relation to
    Cortex-A9 devices only.
V5: Rename remaining "ns" references to "bcm53573", sorry, I sent V4 too
    early.
V6: Drop #include <linux/clk.h>
    Use "int" as type where it matches usage
    Add cpu_relax() in the loop
    Add disable callback
    Use _hw_ functions for registering struct clk_hw (new API)

    Thanks a lot Stephen!
V7: Use syscon and regmap (thanks Rob!)
---
 .../bindings/clock/brcm,bcm53573-ilp.txt           |  36 +++++
 drivers/clk/bcm/Makefile                           |   1 +
 drivers/clk/bcm/clk-bcm53573-ilp.c                 | 148 +++++++++++++++++++++
 3 files changed, 185 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
 create mode 100644 drivers/clk/bcm/clk-bcm53573-ilp.c

diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
new file mode 100644
index 0000000..4554f70
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
@@ -0,0 +1,36 @@
+Broadcom BCM53573 ILP clock
+===========================
+
+This binding uses the common clock binding:
+    Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+This binding is used for ILP clock (sometimes referred as "slow clock")
+on Broadcom BCM53573 devices using Cortex-A7 CPU.
+
+ILP's rate has to be calculated on runtime and it depends on ALP clock
+which has to be referenced.
+
+This clock is part of PMU (Power Management Unit), a Broadcom's device
+handing power-related aspects. Its node must be sub-node of the PMU
+device.
+
+Required properties:
+- compatible: "brcm,bcm53573-ilp"
+- reg: iomem address range of PMU (Power Management Unit)
+- reg-names: "pmu", the only needed & supported reg right now
+- clocks: has to reference an ALP clock
+- #clock-cells: should be <0>
+
+Example:
+
+pmu@18012000 {
+	compatible = "simple-mfd", "syscon";
+	reg = <0x18012000 0x00001000>;
+
+	ilp: ilp@0 {
+		compatible = "brcm,bcm53573-ilp";
+		clocks = <&alp>;
+		#clock-cells = <0>;
+		clock-output-names = "ilp";
+	};
+};
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index 1d79bd2..4b8c56d 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC)	+= clk-ns2.o
 obj-$(CONFIG_ARCH_BCM_CYGNUS)	+= clk-cygnus.o
 obj-$(CONFIG_ARCH_BCM_NSP)	+= clk-nsp.o
 obj-$(CONFIG_ARCH_BCM_5301X)	+= clk-nsp.o
+obj-$(CONFIG_ARCH_BCM_53573)	+= clk-bcm53573-ilp.o
diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c
new file mode 100644
index 0000000..1f4e30d
--- /dev/null
+++ b/drivers/clk/bcm/clk-bcm53573-ilp.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define PMU_XTAL_FREQ_RATIO			0x66c
+#define  XTAL_ALP_PER_4ILP			0x00001fff
+#define  XTAL_CTL_EN				0x80000000
+#define PMU_SLOW_CLK_PERIOD			0x6dc
+
+struct bcm53573_ilp {
+	struct clk_hw hw;
+	struct regmap *regmap;
+};
+
+static int bcm53573_ilp_enable(struct clk_hw *hw)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+
+	regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0x10199);
+	regmap_write(ilp->regmap, 0x674, 0x10000);
+
+	return 0;
+}
+
+static void bcm53573_ilp_disable(struct clk_hw *hw)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+
+	regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0);
+	regmap_write(ilp->regmap, 0x674, 0);
+}
+
+static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
+					      unsigned long parent_rate)
+{
+	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+	struct regmap *regmap = ilp->regmap;
+	u32 last_val, cur_val;
+	int sum = 0, num = 0, loop_num = 0;
+	int avg;
+
+	/* Enable measurement */
+	regmap_write(regmap, PMU_XTAL_FREQ_RATIO, XTAL_CTL_EN);
+
+	/* Read initial value */
+	regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &last_val);
+	last_val &= XTAL_ALP_PER_4ILP;
+
+	/*
+	 * At minimum we should loop for a bit to let hardware do the
+	 * measurement. This isn't very accurate however, so for a better
+	 * precision lets try getting 20 different values for and use average.
+	 */
+	while (num < 20) {
+		regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &cur_val);
+		cur_val &= XTAL_ALP_PER_4ILP;
+
+		if (cur_val != last_val) {
+			/* Got different value, use it */
+			sum += cur_val;
+			num++;
+			loop_num = 0;
+			last_val = cur_val;
+		} else if (++loop_num > 5000) {
+			/* Same value over and over, give up */
+			sum += cur_val;
+			num++;
+			break;
+		}
+
+		cpu_relax();
+	}
+
+	/* Disable measurement to save power */
+	regmap_write(regmap, PMU_XTAL_FREQ_RATIO, 0x0);
+
+	avg = sum / num;
+
+	return parent_rate * 4 / avg;
+}
+
+static const struct clk_ops bcm53573_ilp_clk_ops = {
+	.enable = bcm53573_ilp_enable,
+	.disable = bcm53573_ilp_disable,
+	.recalc_rate = bcm53573_ilp_recalc_rate,
+};
+
+static void bcm53573_ilp_init(struct device_node *np)
+{
+	struct bcm53573_ilp *ilp;
+	struct clk_init_data init = { 0 };
+	const char *parent_name;
+	int err;
+
+	ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
+	if (!ilp)
+		return;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+	if (!parent_name) {
+		err = -ENOENT;
+		goto err_free_ilp;
+	}
+
+	ilp->regmap = syscon_node_to_regmap(of_get_parent(np));
+	if (IS_ERR(ilp->regmap)) {
+		err = PTR_ERR(ilp->regmap);
+		goto err_free_ilp;
+	}
+
+	init.name = np->name;
+	init.ops = &bcm53573_ilp_clk_ops;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	ilp->hw.init = &init;
+	err = clk_hw_register(NULL, &ilp->hw);
+	if (err)
+		goto err_free_ilp;
+
+	err = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &ilp->hw);
+	if (err)
+		goto err_clk_hw_unregister;
+
+	return;
+
+err_clk_hw_unregister:
+	clk_hw_unregister(&ilp->hw);
+err_free_ilp:
+	kfree(ilp);
+	pr_err("Failed to init ILP clock: %d\n", err);
+}
+
+/* We need it very early for arch code, before device model gets ready */
+CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);
-- 
2.9.3

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