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[PATCH v5 0/8] Add board support for TS-4600

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  [PATCH v5 0/8] Add board support for TS-4600 Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com> - 2017-07-14 22:40 +0200
    [PATCH v5 6/8] dt-bindings: watchdog: add documentation for TS4600 watchdog controller Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com> - 2017-07-14 22:40 +0200
    [PATCH v5 4/8] bus: add driver for the Technologic Systems NBUS Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com> - 2017-07-14 22:40 +0200

#1687660 — [PATCH v5 0/8] Add board support for TS-4600

This patch serie adds support for the TS-4600 boards rev A and B. These
boards, manufactured by Technologic Systems, are based on an i.MX28.

This serie include the support for the watchdog which could be enable
at Linux boot time depending on the bootloader.

The watchdog and few peripherals are implemented in a FPGA, and can
only be access using a custom GPIOs bit-banged bus which is called the
NBUS by Technologic Systems.
A driver for this bus is also included and used by the watchdog.

Sebastien Bourdelin (8):
  of: documentation: add bindings documentation for TS-4600
  ARM: dts: TS-4600: add basic device tree
  dt-bindings: bus: Add documentation for the Technologic Systems NBUS
  bus: add driver for the Technologic Systems NBUS
  ARM: dts: TS-4600: add NBUS support
  dt-bindings: watchdog: add documentation for TS4600 watchdog
    controller
  watchdog: TS-4600: add driver for TS-4600 watchdog controller
  ARM: dts: TS-4600: add watchdog support

 .../devicetree/bindings/arm/technologic.txt        |   5 +
 Documentation/devicetree/bindings/bus/ts-nbus.txt  |  50 +++
 .../devicetree/bindings/watchdog/ts4600-wdt.txt    |  16 +
 arch/arm/boot/dts/Makefile                         |   2 +
 arch/arm/boot/dts/imx28-ts4600-common.dtsi         | 126 +++++++
 arch/arm/boot/dts/imx28-ts4600-rev-a.dts           |  22 ++
 arch/arm/boot/dts/imx28-ts4600-rev-b.dts           |  22 ++
 drivers/bus/Kconfig                                |   8 +
 drivers/bus/Makefile                               |   1 +
 drivers/bus/ts-nbus.c                              | 375 +++++++++++++++++++++
 drivers/watchdog/Kconfig                           |  11 +
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/ts4600_wdt.c                      | 185 ++++++++++
 include/linux/ts-nbus.h                            |  18 +
 14 files changed, 842 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/ts-nbus.txt
 create mode 100644 Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt
 create mode 100644 arch/arm/boot/dts/imx28-ts4600-common.dtsi
 create mode 100644 arch/arm/boot/dts/imx28-ts4600-rev-a.dts
 create mode 100644 arch/arm/boot/dts/imx28-ts4600-rev-b.dts
 create mode 100644 drivers/bus/ts-nbus.c
 create mode 100644 drivers/watchdog/ts4600_wdt.c
 create mode 100644 include/linux/ts-nbus.h

-- 
2.13.0

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#1687661 — [PATCH v5 6/8] dt-bindings: watchdog: add documentation for TS4600 watchdog controller

This patch adds dt-binding documentation for TS4600 watchdog controller.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
---
Changes v4 -> v5:
  - fix missing signed off

v4:
  - this documentation was previously merged with the watchdog driver
  and had been acked by Rob Herring, no changes have been done since.
---
 .../devicetree/bindings/watchdog/ts4600-wdt.txt          | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt

diff --git a/Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt b/Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt
new file mode 100644
index 000000000000..7de00ceae341
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt
@@ -0,0 +1,16 @@
+TS-4600 Technologic Systems Watchdog
+
+Required properties:
+- compatible: must be "technologic,ts4600-wdt"
+- reg: offset to the FPGA's watchdog register
+
+Optional property:
+- timeout-sec: contains the watchdog timeout in seconds.
+
+Example:
+
+watchdog {
+	compatible = "technologic,ts4600-wdt";
+	reg = <0x2a>;
+	timeout-sec = <10>;
+};
-- 
2.13.0

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#1687662 — [PATCH v5 4/8] bus: add driver for the Technologic Systems NBUS

This driver implements a GPIOs bit-banged bus, called the NBUS by
Technologic Systems. It is used to communicate with the peripherals in
the FPGA on the TS-4600 SoM.

Signed-off-by: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
---
Changes v4 -> v5:
  - fix missing signed off

Changes v3 -> v4:
  - rebase on master
  - fix vendor prefixes for dts properties (suggested by Rob Herring)
  - v3 was acked by Linus Walleij

Changes v2 -> v3:
  - rebase on master
  - remove all call to the "inline" keyword in functions to let the
  compiler decide when required (suggested by Linus Walleij)
  - move the struct ts_nbus to the driver code instead of its header
  file (suggested by Linus Walleij)
  - use the bitops header and the BIT macro (suggested by Linus Walleij)
  - move the mutex to the struct ts_nbus instead to have it statically
  declared in the driver code (suggested by Linus Walleij)
  - remove the ts_nbus_set_mode function to simplify the logic
  (suggested by Linus Walleij)
  - the nbus will always need 8 data lines, remove the use of the
  ndescs when dealing with the data gpios and hardcode the value for
  simplicity instead (suggested by Linus Walleij)
  - add more comments (suggested by Linus Walleij)
  - rework all the ts_nbus_read_... functions to propagate the
  gpiod_get_value_... errno code (suggested by Linus Walleij)
  - few typos and code reformating for lisibility

Changes v1 -> v2:
  - rebase on master
  - the driver now populate its child nodes
  - remove the 'default y' option from the Kconfig
  - rework the driver to not use singleton anymore (suggested by Linus
  Walleij)
  - replace the use of the legacy GPIO API with gpiod (suggested by
  Linus Walleij)
  - use the ts vendor prefix for gpios (suggested by Rob Herring)
---
 drivers/bus/Kconfig     |   8 ++
 drivers/bus/Makefile    |   1 +
 drivers/bus/ts-nbus.c   | 375 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/ts-nbus.h |  18 +++
 4 files changed, 402 insertions(+)
 create mode 100644 drivers/bus/ts-nbus.c
 create mode 100644 include/linux/ts-nbus.h

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 2408ea38a39c..3465e0decac5 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -157,6 +157,14 @@ config TEGRA_GMI
 	  Driver for the Tegra Generic Memory Interface bus which can be used
 	  to attach devices such as NOR, UART, FPGA and more.
 
+config TS_NBUS
+	tristate "Technologic Systems NBUS Driver"
+	depends on SOC_IMX28
+	depends on OF_GPIO && PWM
+	help
+	  Driver for the Technologic Systems NBUS which is used to interface
+	  with the peripherals in the FPGA of the TS-4600 SoM.
+
 config UNIPHIER_SYSTEM_BUS
 	tristate "UniPhier System Bus driver"
 	depends on ARCH_UNIPHIER && OF
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index cc6364bec054..72377f77651c 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
 obj-$(CONFIG_SIMPLE_PM_BUS)	+= simple-pm-bus.o
 obj-$(CONFIG_TEGRA_ACONNECT)	+= tegra-aconnect.o
 obj-$(CONFIG_TEGRA_GMI)		+= tegra-gmi.o
+obj-$(CONFIG_TS_NBUS)		+= ts-nbus.o
 obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
 
diff --git a/drivers/bus/ts-nbus.c b/drivers/bus/ts-nbus.c
new file mode 100644
index 000000000000..073fd9011154
--- /dev/null
+++ b/drivers/bus/ts-nbus.c
@@ -0,0 +1,375 @@
+/*
+ * NBUS driver for TS-4600 based boards
+ *
+ * Copyright (c) 2016 - Savoir-faire Linux
+ * Author: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * This driver implements a GPIOs bit-banged bus, called the NBUS by Technologic
+ * Systems. It is used to communicate with the peripherals in the FPGA on the
+ * TS-4600 SoM.
+ */
+
+#include <linux/bitops.h>
+#include <linux/gpio/consumer.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/ts-nbus.h>
+
+#define TS_NBUS_DIRECTION_IN  0
+#define TS_NBUS_DIRECTION_OUT 1
+#define TS_NBUS_WRITE_ADR 0
+#define TS_NBUS_WRITE_VAL 1
+
+struct ts_nbus {
+	struct pwm_device *pwm;
+	struct gpio_descs *data;
+	struct gpio_desc *csn;
+	struct gpio_desc *txrx;
+	struct gpio_desc *strobe;
+	struct gpio_desc *ale;
+	struct gpio_desc *rdy;
+	struct mutex lock;
+};
+
+/*
+ * request all gpios required by the bus.
+ */
+static int ts_nbus_init_pdata(struct platform_device *pdev, struct ts_nbus
+		*ts_nbus)
+{
+	ts_nbus->data = devm_gpiod_get_array(&pdev->dev, "ts,data",
+			GPIOD_OUT_HIGH);
+	if (IS_ERR(ts_nbus->data)) {
+		dev_err(&pdev->dev, "failed to retrieve ts,data-gpio from dts\n");
+		return PTR_ERR(ts_nbus->data);
+	}
+
+	ts_nbus->csn = devm_gpiod_get(&pdev->dev, "ts,csn", GPIOD_OUT_HIGH);
+	if (IS_ERR(ts_nbus->csn)) {
+		dev_err(&pdev->dev, "failed to retrieve ts,csn-gpio from dts\n");
+		return PTR_ERR(ts_nbus->csn);
+	}
+
+	ts_nbus->txrx = devm_gpiod_get(&pdev->dev, "ts,txrx", GPIOD_OUT_HIGH);
+	if (IS_ERR(ts_nbus->txrx)) {
+		dev_err(&pdev->dev, "failed to retrieve ts,txrx-gpio from dts\n");
+		return PTR_ERR(ts_nbus->txrx);
+	}
+
+	ts_nbus->strobe = devm_gpiod_get(&pdev->dev, "ts,strobe", GPIOD_OUT_HIGH);
+	if (IS_ERR(ts_nbus->strobe)) {
+		dev_err(&pdev->dev, "failed to retrieve ts,strobe-gpio from dts\n");
+		return PTR_ERR(ts_nbus->strobe);
+	}
+
+	ts_nbus->ale = devm_gpiod_get(&pdev->dev, "ts,ale", GPIOD_OUT_HIGH);
+	if (IS_ERR(ts_nbus->ale)) {
+		dev_err(&pdev->dev, "failed to retrieve ts,ale-gpio from dts\n");
+		return PTR_ERR(ts_nbus->ale);
+	}
+
+	ts_nbus->rdy = devm_gpiod_get(&pdev->dev, "ts,rdy", GPIOD_IN);
+	if (IS_ERR(ts_nbus->rdy)) {
+		dev_err(&pdev->dev, "failed to retrieve ts,rdy-gpio from dts\n");
+		return PTR_ERR(ts_nbus->rdy);
+	}
+
+	return 0;
+}
+
+/*
+ * the data gpios are used for reading and writing values, their directions
+ * should be adjusted accordingly.
+ */
+static void ts_nbus_set_direction(struct ts_nbus *ts_nbus, int direction)
+{
+	int i;
+
+	for (i = 0; i < 8; i++) {
+		if (direction == TS_NBUS_DIRECTION_IN)
+			gpiod_direction_input(ts_nbus->data->desc[i]);
+		else
+			/* when used as output the default state of the data
+			 * lines are set to high */
+			gpiod_direction_output(ts_nbus->data->desc[i], 1);
+	}
+}
+
+/*
+ * reset the bus in its initial state.
+ * The data, csn, strobe and ale lines must be zero'ed to let the FPGA knows a
+ * new transaction can be process.
+ */
+static void ts_nbus_reset_bus(struct ts_nbus *ts_nbus)
+{
+	int i;
+	int values[8];
+
+	for (i = 0; i < 8; i++)
+		values[i] = 0;
+
+	gpiod_set_array_value_cansleep(8, ts_nbus->data->desc, values);
+	gpiod_set_value_cansleep(ts_nbus->csn, 0);
+	gpiod_set_value_cansleep(ts_nbus->strobe, 0);
+	gpiod_set_value_cansleep(ts_nbus->ale, 0);
+}
+
+/*
+ * let the FPGA knows it can process.
+ */
+static void ts_nbus_start_transaction(struct ts_nbus *ts_nbus)
+{
+	gpiod_set_value_cansleep(ts_nbus->strobe, 1);
+}
+
+/*
+ * read a byte value from the data gpios.
+ * return 0 on success or negative errno on failure.
+ */
+static int ts_nbus_read_byte(struct ts_nbus *ts_nbus, u8 *val)
+{
+	struct gpio_descs *gpios = ts_nbus->data;
+	int ret, i;
+
+	*val = 0;
+	for (i = 0; i < 8; i++) {
+		ret = gpiod_get_value_cansleep(gpios->desc[i]);
+		if (ret < 0)
+			return ret;
+		if (ret)
+			*val |= BIT(i);
+	}
+
+	return 0;
+}
+
+/*
+ * set the data gpios accordingly to the byte value.
+ */
+static void ts_nbus_write_byte(struct ts_nbus *ts_nbus, u8 byte)
+{
+	struct gpio_descs *gpios = ts_nbus->data;
+	int i;
+	int values[8];
+
+	for (i = 0; i < 8; i++)
+		if (byte & BIT(i))
+			values[i] = 1;
+		else
+			values[i] = 0;
+
+	gpiod_set_array_value_cansleep(8, gpios->desc, values);
+}
+
+/*
+ * reading the bus consists of resetting the bus, then notifying the FPGA to
+ * send the data in the data gpios and return the read value.
+ * return 0 on success or negative errno on failure.
+ */
+static int ts_nbus_read_bus(struct ts_nbus *ts_nbus, u8 *val)
+{
+	ts_nbus_reset_bus(ts_nbus);
+	ts_nbus_start_transaction(ts_nbus);
+
+	return ts_nbus_read_byte(ts_nbus, val);
+}
+
+/*
+ * writing to the bus consists of resetting the bus, then define the type of
+ * command (address/value), write the data and notify the FPGA to retrieve the
+ * value in the data gpios.
+ */
+static void ts_nbus_write_bus(struct ts_nbus *ts_nbus, int cmd, u8 val)
+{
+	ts_nbus_reset_bus(ts_nbus);
+
+	if (cmd == TS_NBUS_WRITE_ADR)
+		gpiod_set_value_cansleep(ts_nbus->ale, 1);
+
+	ts_nbus_write_byte(ts_nbus, val);
+	ts_nbus_start_transaction(ts_nbus);
+}
+
+/*
+ * read the value in the FPGA register at the given address.
+ * return 0 on success or negative errno on failure.
+ */
+int ts_nbus_read(struct ts_nbus *ts_nbus, u8 adr, u16 *val)
+{
+	int ret, i;
+	u8 byte;
+
+	/* bus access must be atomic */
+	mutex_lock(&ts_nbus->lock);
+
+	/* set the bus in read mode */
+	gpiod_set_value_cansleep(ts_nbus->txrx, 0);
+
+	/* write address */
+	ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr);
+
+	/* set the data gpios direction as input before reading */
+	ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_IN);
+
+	/* reading value MSB first */
+	do {
+		*val = 0;
+		byte = 0;
+		for (i = 1; i >= 0; i--) {
+			/* read a byte from the bus, leave on error */
+			ret = ts_nbus_read_bus(ts_nbus, &byte);
+			if (ret < 0)
+				goto err;
+
+			/* append the byte read to the final value */
+			*val |= byte << (i * 8);
+		}
+		gpiod_set_value_cansleep(ts_nbus->csn, 1);
+		ret = gpiod_get_value_cansleep(ts_nbus->rdy);
+	} while (ret);
+
+err:
+	/* restore the data gpios direction as output after reading */
+	ts_nbus_set_direction(ts_nbus, TS_NBUS_DIRECTION_OUT);
+
+	mutex_unlock(&ts_nbus->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ts_nbus_read);
+
+/*
+ * write the desired value in the FPGA register at the given address.
+ */
+int ts_nbus_write(struct ts_nbus *ts_nbus, u8 adr, u16 val)
+{
+	int i;
+
+	/* bus access must be atomic */
+	mutex_lock(&ts_nbus->lock);
+
+	/* set the bus in write mode */
+	gpiod_set_value_cansleep(ts_nbus->txrx, 1);
+
+	/* write address */
+	ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_ADR, adr);
+
+	/* writing value MSB first */
+	for (i = 1; i >= 0; i--)
+		ts_nbus_write_bus(ts_nbus, TS_NBUS_WRITE_VAL, (u8)(val >> (i * 8)));
+
+	/* wait for completion */
+	gpiod_set_value_cansleep(ts_nbus->csn, 1);
+	while (gpiod_get_value_cansleep(ts_nbus->rdy) != 0) {
+		gpiod_set_value_cansleep(ts_nbus->csn, 0);
+		gpiod_set_value_cansleep(ts_nbus->csn, 1);
+	}
+
+	mutex_unlock(&ts_nbus->lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ts_nbus_write);
+
+static int ts_nbus_probe(struct platform_device *pdev)
+{
+	struct pwm_device *pwm;
+	struct pwm_args pargs;
+	struct device *dev = &pdev->dev;
+	struct ts_nbus *ts_nbus;
+	int ret;
+
+	ts_nbus = devm_kzalloc(dev, sizeof(*ts_nbus), GFP_KERNEL);
+	if (!ts_nbus)
+		return -ENOMEM;
+
+	mutex_init(&ts_nbus->lock);
+
+	ret = ts_nbus_init_pdata(pdev, ts_nbus);
+	if (ret < 0)
+		return ret;
+
+	pwm = devm_pwm_get(dev, NULL);
+	if (IS_ERR(pwm)) {
+		ret = PTR_ERR(pwm);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "unable to request PWM\n");
+		return ret;
+	}
+
+	pwm_get_args(pwm, &pargs);
+	if (!pargs.period) {
+		dev_err(&pdev->dev, "invalid PWM period\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * FIXME: pwm_apply_args() should be removed when switching to
+	 * the atomic PWM API.
+	 */
+	pwm_apply_args(pwm);
+	ret = pwm_config(pwm, pargs.period, pargs.period);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * we can now start the FPGA and populate the peripherals.
+	 */
+	pwm_enable(pwm);
+	ts_nbus->pwm = pwm;
+
+	/*
+	 * let the child nodes retrieve this instance of the ts-nbus.
+	 */
+	dev_set_drvdata(dev, ts_nbus);
+
+	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
+	if (ret < 0)
+		return ret;
+
+	dev_info(dev, "initialized\n");
+
+	return 0;
+}
+
+static int ts_nbus_remove(struct platform_device *pdev)
+{
+	struct ts_nbus *ts_nbus = dev_get_drvdata(&pdev->dev);
+
+	/* shutdown the FPGA */
+	mutex_lock(&ts_nbus->lock);
+	pwm_disable(ts_nbus->pwm);
+	mutex_unlock(&ts_nbus->lock);
+
+	return 0;
+}
+
+static const struct of_device_id ts_nbus_of_match[] = {
+	{ .compatible = "technologic,ts-nbus", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ts_nbus_of_match);
+
+static struct platform_driver ts_nbus_driver = {
+	.probe		= ts_nbus_probe,
+	.remove		= ts_nbus_remove,
+	.driver		= {
+		.name	= "ts_nbus",
+		.of_match_table = ts_nbus_of_match,
+	},
+};
+
+module_platform_driver(ts_nbus_driver);
+
+MODULE_ALIAS("platform:ts_nbus");
+MODULE_AUTHOR("Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>");
+MODULE_DESCRIPTION("Technologic Systems NBUS");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/ts-nbus.h b/include/linux/ts-nbus.h
new file mode 100644
index 000000000000..5bd4c822f7cf
--- /dev/null
+++ b/include/linux/ts-nbus.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2016 - Savoir-faire Linux
+ * Author: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef _TS_NBUS_H
+#define _TS_NBUS_H
+
+struct ts_nbus;
+
+extern int ts_nbus_read(struct ts_nbus *ts_nbus, u8 adr, u16 *val);
+extern int ts_nbus_write(struct ts_nbus *ts_nbus, u8 adr, u16 val);
+
+#endif /* _TS_NBUS_H */
-- 
2.13.0

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