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[PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary peripheral clock gates.

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  [PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary peripheral clock gates. Eric Anholt <eric@anholt.net> - 2015-09-11 00:30 +0200
    Re: [PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary peripheral clock gates. Martin Sperl <martin@sperl.org> - 2015-09-11 12:30 +0200
    Re: [PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary  peripheral clock gates. Stephen Warren <swarren@wwwdotorg.org> - 2015-09-22 04:20 +0200
    Re: [PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary  peripheral clock gates. Stephen Boyd <sboyd@codeaurora.org> - 2015-10-02 02:20 +0200

#1222412 — [PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary peripheral clock gates.

There are a pair of SPI masters and a mini UART that were last minute
additions.  As a result, they didn't get integrated in the same way as
the other gates off of the VPU clock in CPRMAN.

Signed-off-by: Eric Anholt <eric@anholt.net>
---
 drivers/clk/bcm/Makefile          |  1 +
 drivers/clk/bcm/clk-bcm2835-aux.c | 80 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100644 drivers/clk/bcm/clk-bcm2835-aux.c

diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index ee2349b..3082d68 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -4,4 +4,5 @@ obj-$(CONFIG_CLK_BCM_KONA)	+= clk-bcm281xx.o
 obj-$(CONFIG_CLK_BCM_KONA)	+= clk-bcm21664.o
 obj-$(CONFIG_COMMON_CLK_IPROC)	+= clk-iproc-armpll.o clk-iproc-pll.o clk-iproc-asiu.o
 obj-$(CONFIG_ARCH_BCM2835)	+= clk-bcm2835.o
+obj-$(CONFIG_ARCH_BCM2835)	+= clk-bcm2835-aux.o
 obj-$(CONFIG_ARCH_BCM_CYGNUS)	+= clk-cygnus.o
diff --git a/drivers/clk/bcm/clk-bcm2835-aux.c b/drivers/clk/bcm/clk-bcm2835-aux.c
new file mode 100644
index 0000000..1efa6fb
--- /dev/null
+++ b/drivers/clk/bcm/clk-bcm2835-aux.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/bcm2835.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <dt-bindings/clock/bcm2835-aux.h>
+
+static int bcm2835_aux_clk_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct clk_onecell_data *onecell;
+	const char *parent;
+	struct clk *parent_clk;
+	void __iomem *reg;
+
+	parent_clk = of_clk_get(dev->of_node, 0);
+	if (IS_ERR(parent_clk))
+		return PTR_ERR(parent_clk);
+	parent = __clk_get_name(parent_clk);
+
+	reg = of_iomap(dev->of_node, 0);
+	if (!reg)
+		return -ENODEV;
+
+	onecell = kmalloc(sizeof(*onecell), GFP_KERNEL);
+	if (!onecell)
+		return -ENOMEM;
+	onecell->clk_num = BCM2835_AUX_CLOCK_COUNT;
+	onecell->clks = kzalloc(sizeof(*onecell->clks) *
+				BCM2835_AUX_CLOCK_COUNT, GFP_KERNEL);
+	if (!onecell->clks)
+		return -ENOMEM;
+
+	onecell->clks[BCM2835_AUX_CLOCK_UART] =
+		clk_register_gate(dev, "aux_uart", parent, 0, reg, 0, 0, NULL);
+
+	onecell->clks[BCM2835_AUX_CLOCK_SPI1] =
+		clk_register_gate(dev, "aux_spi1", parent, 0, reg, 1, 0, NULL);
+
+	onecell->clks[BCM2835_AUX_CLOCK_SPI2] =
+		clk_register_gate(dev, "aux_spi2", parent, 0, reg, 2, 0, NULL);
+
+	return of_clk_add_provider(pdev->dev.of_node, of_clk_src_onecell_get,
+				   onecell);
+}
+
+static const struct of_device_id bcm2835_aux_clk_of_match[] = {
+	{ .compatible = "brcm,bcm2835-aux-clock", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm2835_aux_clk_of_match);
+
+static struct platform_driver bcm2835_aux_clk_driver = {
+	.driver = {
+		.name = "bcm2835-aux-clk",
+		.of_match_table = bcm2835_aux_clk_of_match,
+	},
+	.probe          = bcm2835_aux_clk_probe,
+};
+builtin_platform_driver(bcm2835_aux_clk_driver);
+
+MODULE_AUTHOR("Eric Anholt <eric@anholt.net>");
+MODULE_DESCRIPTION("BCM2835 auxiliary peripheral clock driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4

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#1222698

> On 11.09.2015, at 00:22, Eric Anholt <eric@anholt.net> wrote:
> 
> There are a pair of SPI masters and a mini UART that were last minute
> additions.  As a result, they didn't get integrated in the same way as
> the other gates off of the VPU clock in CPRMAN.
> 
> Signed-off-by: Eric Anholt <eric@anholt.net>
> ---

Tested with the spi-bcm2835aux driver and it works perfectly.
I will now post the latest incarnation of the driver for inclusion.

I have also tested with the uart1 and it works in principle.

Note that there is one issue (as mentioned elsewhere) with uart1:
the 8250 serial driver has a (hardcoded) internal clock divider 16,
while the hardware has an internal divider of 8.

This results in baud rates that are a factor of 2 higher than requested.

Tested-by: Martin Sperl <kernel@martin.sperl.org>

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#1229881 — Re: [PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary peripheral clock gates.

On 09/10/2015 03:22 PM, Eric Anholt wrote:
> There are a pair of SPI masters and a mini UART that were last minute
> additions.  As a result, they didn't get integrated in the same way as
> the other gates off of the VPU clock in CPRMAN.

> diff --git a/drivers/clk/bcm/clk-bcm2835-aux.c b/drivers/clk/bcm/clk-bcm2835-aux.c

> +static int bcm2835_aux_clk_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct clk_onecell_data *onecell;
> +	const char *parent;
> +	struct clk *parent_clk;
> +	void __iomem *reg;
> +
> +	parent_clk = of_clk_get(dev->of_node, 0);
> +	if (IS_ERR(parent_clk))
> +		return PTR_ERR(parent_clk);
> +	parent = __clk_get_name(parent_clk);

I think all the comments I made on probe() for the main bcm2835 clock
driver likely apply here too.

Also, is it "legal" for clock drivers to use __clk_get_name()? I thought
that was a clock core internal function, but may be wrong. I would have
expected to be able to pass a clock object when registering clocks
rather than a clock name, but oh well.

BTW, I like how this series shows how useful it is for someone with full
knowledge of the HW to come up with the DT bindings for a HW module;
once you know how the HW is actually designed, the correct binding ends
up being a lot easier to come up with, rather than guessing:-)
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#1237845 — Re: [PATCH 2/3] clk: bcm2835: Add a driver for the auxiliary peripheral clock gates.

On 09/10, Eric Anholt wrote:
> diff --git a/drivers/clk/bcm/clk-bcm2835-aux.c b/drivers/clk/bcm/clk-bcm2835-aux.c
> new file mode 100644
> index 0000000..1efa6fb
> --- /dev/null
> +++ b/drivers/clk/bcm/clk-bcm2835-aux.c
> @@ -0,0 +1,80 @@
> +/*
> + * Copyright (C) 2015 Broadcom
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/clkdev.h>

Is this include used?

> +#include <linux/clk/bcm2835.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <dt-bindings/clock/bcm2835-aux.h>
> +
> +static int bcm2835_aux_clk_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct clk_onecell_data *onecell;
> +	const char *parent;
> +	struct clk *parent_clk;
> +	void __iomem *reg;
> +
> +	parent_clk = of_clk_get(dev->of_node, 0);
> +	if (IS_ERR(parent_clk))
> +		return PTR_ERR(parent_clk);

We have a device, any reason we can't use clk_get() directly?

> +	parent = __clk_get_name(parent_clk);
> +
> +	reg = of_iomap(dev->of_node, 0);

We have a platform device here, why aren't we using platform
device APIs like platform_get_resource() and
devm_ioremap_resource()?

> +	if (!reg)
> +		return -ENODEV;
> +
> +	onecell = kmalloc(sizeof(*onecell), GFP_KERNEL);
> +	if (!onecell)
> +		return -ENOMEM;
> +	onecell->clk_num = BCM2835_AUX_CLOCK_COUNT;
> +	onecell->clks = kzalloc(sizeof(*onecell->clks) *

kcalloc?

> +				BCM2835_AUX_CLOCK_COUNT, GFP_KERNEL);
> +	if (!onecell->clks)
> +		return -ENOMEM;
> +

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