[PATCH v3 0/2] GPIO: add single-register GPIO via CREG driver

[PATCH v3 0/2] GPIO: add single-register GPIO via CREG driver

[Eugeniy Paltsev]

Add single-register MMIO GPIO driver for complex cases where
only several fields in register belong to GPIO lines and each GPIO
line owns a field with different length and on/off value.

Such CREG GPIOs are used in Synopsys AXS10x and HSDK boards.

Changes v2->v3:
 * Move parameters into a lookup table instead of device tree.
 * Use the ngpios attribute for instead of snps,ngpios.

Eugeniy Paltsev (2):
  GPIO: add single-register GPIO via CREG driver
  dt-bindings: Document the Synopsys GPIO via CREG bindings

 .../devicetree/bindings/gpio/snps,creg-gpio.txt    |  18 ++
 MAINTAINERS                                        |   6 +
 drivers/gpio/Kconfig                               |  10 +
 drivers/gpio/Makefile                              |   1 +
 drivers/gpio/gpio-creg-snps.c                      | 212 +++++++++++++++++++++
 5 files changed, 247 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt
 create mode 100644 drivers/gpio/gpio-creg-snps.c

-- 
2.14.4

[PATCH v3 1/2] GPIO: add single-register GPIO via CREG driver

[Eugeniy Paltsev]

Add single-register MMIO GPIO driver for complex cases where
only several fields in register belong to GPIO lines and each GPIO
line owns a field with different length and on/off value.

Such CREG GPIOs are used in Synopsys AXS10x and HSDK boards.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
Changes v2->v3:
 * Move parameters into a lookup table instead of device tree.
 * Use the ngpios attribute for instead of snps,ngpios.

 MAINTAINERS                   |   6 ++
 drivers/gpio/Kconfig          |  10 ++
 drivers/gpio/Makefile         |   1 +
 drivers/gpio/gpio-creg-snps.c | 212 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 229 insertions(+)
 create mode 100644 drivers/gpio/gpio-creg-snps.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 544cac829cf4..e731f2f9648a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13734,6 +13734,12 @@ S:	Supported
 F:	drivers/reset/reset-axs10x.c
 F:	Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
 
+SYNOPSYS CREG GPIO DRIVER
+M:	Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+S:	Maintained
+F:	drivers/gpio/gpio-creg-snps.c
+F:	Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt
+
 SYNOPSYS DESIGNWARE 8250 UART DRIVER
 R:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 S:	Maintained
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 71c0ab46f216..78155ac22b0c 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -430,6 +430,16 @@ config GPIO_REG
 	  A 32-bit single register GPIO fixed in/out implementation.  This
 	  can be used to represent any register as a set of GPIO signals.
 
+config GPIO_SNPS_CREG
+	bool "Synopsys GPIO via CREG (Control REGisters) driver"
+	depends on ARC || COMPILE_TEST
+	select OF_GPIO
+	help
+	  This driver supports GPIOs via CREG on various Synopsys SoCs.
+	  This is a single-register MMIO GPIO driver for complex cases
+	  where only several fields in register belong to GPIO lines and
+	  each GPIO line owns a field with different length and on/off value.
+
 config GPIO_SPEAR_SPICS
 	bool "ST SPEAr13xx SPI Chip Select as GPIO support"
 	depends on PLAT_SPEAR
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 1324c8f966a7..993f8ad54a19 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -109,6 +109,7 @@ obj-$(CONFIG_GPIO_REG)		+= gpio-reg.o
 obj-$(CONFIG_ARCH_SA1100)	+= gpio-sa1100.o
 obj-$(CONFIG_GPIO_SCH)		+= gpio-sch.o
 obj-$(CONFIG_GPIO_SCH311X)	+= gpio-sch311x.o
+obj-$(CONFIG_GPIO_SNPS_CREG)	+= gpio-creg-snps.o
 obj-$(CONFIG_GPIO_SODAVILLE)	+= gpio-sodaville.o
 obj-$(CONFIG_GPIO_SPEAR_SPICS)	+= gpio-spear-spics.o
 obj-$(CONFIG_GPIO_SPRD)		+= gpio-sprd.o
diff --git a/drivers/gpio/gpio-creg-snps.c b/drivers/gpio/gpio-creg-snps.c
new file mode 100644
index 000000000000..2400dec529b2
--- /dev/null
+++ b/drivers/gpio/gpio-creg-snps.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Synopsys CREG (Control REGisters) GPIO driver
+//
+// Copyright (C) 2018 Synopsys
+// Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+
+#include <linux/of.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/of_gpio.h>
+#include <linux/io.h>
+#include <linux/of_platform.h>
+#include <linux/module.h>
+
+#include "gpiolib.h"
+
+#define MAX_GPIO	32
+
+struct creg_layout {
+	u8 ngpio;
+	u8 shift[MAX_GPIO];
+	u8 on[MAX_GPIO];
+	u8 off[MAX_GPIO];
+	u8 bit_per_gpio[MAX_GPIO];
+};
+
+struct creg_gpio {
+	struct of_mm_gpio_chip mmchip;
+	spinlock_t lock;
+	const struct creg_layout *layout;
+};
+
+static void creg_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	struct creg_gpio *hcg = gpiochip_get_data(gc);
+	const struct creg_layout *layout = hcg->layout;
+	u32 reg, reg_shift, value;
+	unsigned long flags;
+	int i;
+
+	value = val ? hcg->layout->on[gpio] : hcg->layout->off[gpio];
+
+	reg_shift = layout->shift[gpio];
+	for (i = 0; i < gpio; i++)
+		reg_shift += layout->bit_per_gpio[i] + layout->shift[i];
+
+	spin_lock_irqsave(&hcg->lock, flags);
+	reg = readl(hcg->mmchip.regs);
+	reg &= ~(GENMASK(layout->bit_per_gpio[i] - 1, 0) << reg_shift);
+	reg |=  (value << reg_shift);
+	writel(reg, hcg->mmchip.regs);
+	spin_unlock_irqrestore(&hcg->lock, flags);
+}
+
+static int creg_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	creg_gpio_set(gc, gpio, val);
+
+	return 0;
+}
+
+static int creg_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	return 0; /* output */
+}
+
+static int creg_gpio_xlate(struct gpio_chip *gc,
+			   const struct of_phandle_args *gpiospec, u32 *flags)
+{
+	if (gpiospec->args_count != 1) {
+		dev_err(&gc->gpiodev->dev, "invalid args_count: %d\n",
+			gpiospec->args_count);
+		return -EINVAL;
+	}
+
+	if (gpiospec->args[0] >= gc->ngpio) {
+		dev_err(&gc->gpiodev->dev, "gpio number is too big: %d\n",
+			gpiospec->args[0]);
+		return -EINVAL;
+	}
+
+	return gpiospec->args[0];
+}
+
+static int creg_gpio_validate_pg(struct device *dev, struct creg_gpio *hcg,
+				 int i)
+{
+	const struct creg_layout *layout = hcg->layout;
+
+	if (layout->bit_per_gpio[i] < 1 || layout->bit_per_gpio[i] > 8)
+		return -EINVAL;
+
+	/* Check that on valiue suits it's placeholder */
+	if (GENMASK(31, layout->bit_per_gpio[i]) & layout->on[i])
+		return -EINVAL;
+
+	/* Check that off valiue suits it's placeholder */
+	if (GENMASK(31, layout->bit_per_gpio[i]) & layout->off[i])
+		return -EINVAL;
+
+	if (layout->on[i] == layout->off[i])
+		return -EINVAL;
+
+	return 0;
+}
+
+static int creg_gpio_validate(struct device *dev, struct creg_gpio *hcg,
+			      u32 ngpios)
+{
+	u32 reg_len = 0;
+	int i;
+
+	if (hcg->layout->ngpio < 1 || hcg->layout->ngpio > MAX_GPIO)
+		return -EINVAL;
+
+	if (ngpios < 1 || ngpios > hcg->layout->ngpio) {
+		dev_err(dev, "ngpios must be in [1:%u]\n", hcg->layout->ngpio);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < hcg->layout->ngpio; i++) {
+		if (creg_gpio_validate_pg(dev, hcg, i))
+			return -EINVAL;
+
+		reg_len += hcg->layout->shift[i] + hcg->layout->bit_per_gpio[i];
+	}
+
+	/* Check that we suit in 32 bit register */
+	if (reg_len > 32)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct creg_layout hsdk_cs_ctl = {
+	.ngpio		= 10,
+	.shift		= { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
+	.off		= { 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 },
+	.on		= { 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 },
+	.bit_per_gpio	= { 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 }
+};
+
+static const struct creg_layout axs10x_flsh_cs_ctl = {
+	.ngpio		= 1,
+	.shift		= { 0 },
+	.off		= { 1 },
+	.on		= { 3 },
+	.bit_per_gpio	= { 2 }
+};
+
+static const struct of_device_id creg_gpio_ids[] = {
+	{
+		.compatible = "snps,creg-gpio-axs10x",
+		.data = &axs10x_flsh_cs_ctl
+	}, {
+		.compatible = "snps,creg-gpio-hsdk",
+		.data = &hsdk_cs_ctl
+	}, { /* sentinel */ }
+};
+
+static int creg_gpio_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+	struct device *dev = &pdev->dev;
+	struct creg_gpio *hcg;
+	u32 ngpios;
+	int ret;
+
+	hcg = devm_kzalloc(dev, sizeof(struct creg_gpio), GFP_KERNEL);
+	if (!hcg)
+		return -ENOMEM;
+
+	match = of_match_node(creg_gpio_ids, pdev->dev.of_node);
+	hcg->layout = match->data;
+	if (!hcg->layout)
+		return -EINVAL;
+
+	ret = of_property_read_u32(dev->of_node, "ngpios", &ngpios);
+	if (ret)
+		return ret;
+
+	ret = creg_gpio_validate(dev, hcg, ngpios);
+	if (ret)
+		return ret;
+
+	spin_lock_init(&hcg->lock);
+
+	hcg->mmchip.gc.ngpio = ngpios;
+	hcg->mmchip.gc.set = creg_gpio_set;
+	hcg->mmchip.gc.get_direction = creg_gpio_get_direction;
+	hcg->mmchip.gc.direction_output = creg_gpio_dir_out;
+	hcg->mmchip.gc.of_xlate = creg_gpio_xlate;
+	hcg->mmchip.gc.of_gpio_n_cells = 1;
+
+	ret = of_mm_gpiochip_add_data(pdev->dev.of_node, &hcg->mmchip, hcg);
+	if (ret)
+		return ret;
+
+	dev_info(dev, "GPIO controller with %d gpios probed\n", ngpios);
+
+	return 0;
+}
+
+static struct platform_driver creg_gpio_snps_driver = {
+	.driver = {
+		.name = "snps-creg-gpio",
+		.of_match_table = creg_gpio_ids,
+	},
+	.probe  = creg_gpio_probe,
+};
+builtin_platform_driver(creg_gpio_snps_driver);
-- 
2.14.4

Re: [PATCH v3 1/2] GPIO: add single-register GPIO via CREG driver

[Eugeniy Paltsev]

Hi Linus,

Maybe you have any comments or remarks about this patch? And if you don't could you please apply it.
Thanks!

On Tue, 2018-09-11 at 18:09 +0300, Eugeniy Paltsev wrote:
> Add single-register MMIO GPIO driver for complex cases where
> only several fields in register belong to GPIO lines and each GPIO
> line owns a field with different length and on/off value.
> 
> Such CREG GPIOs are used in Synopsys AXS10x and HSDK boards.
> 
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
> Changes v2->v3:
>  * Move parameters into a lookup table instead of device tree.
>  * Use the ngpios attribute for instead of snps,ngpios.
> 
>  MAINTAINERS                   |   6 ++
>  drivers/gpio/Kconfig          |  10 ++
>  drivers/gpio/Makefile         |   1 +
>  drivers/gpio/gpio-creg-snps.c | 212 ++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 229 insertions(+)
>  create mode 100644 drivers/gpio/gpio-creg-snps.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 544cac829cf4..e731f2f9648a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13734,6 +13734,12 @@ S:	Supported
>  F:	drivers/reset/reset-axs10x.c
>  F:	Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
>  
> +SYNOPSYS CREG GPIO DRIVER
> +M:	Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> +S:	Maintained
> +F:	drivers/gpio/gpio-creg-snps.c
> +F:	Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt
> +
>  SYNOPSYS DESIGNWARE 8250 UART DRIVER
>  R:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>  S:	Maintained
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 71c0ab46f216..78155ac22b0c 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -430,6 +430,16 @@ config GPIO_REG
>  	  A 32-bit single register GPIO fixed in/out implementation.  This
>  	  can be used to represent any register as a set of GPIO signals.
>  
> +config GPIO_SNPS_CREG
> +	bool "Synopsys GPIO via CREG (Control REGisters) driver"
> +	depends on ARC || COMPILE_TEST
> +	select OF_GPIO
> +	help
> +	  This driver supports GPIOs via CREG on various Synopsys SoCs.
> +	  This is a single-register MMIO GPIO driver for complex cases
> +	  where only several fields in register belong to GPIO lines and
> +	  each GPIO line owns a field with different length and on/off value.
> +
>  config GPIO_SPEAR_SPICS
>  	bool "ST SPEAr13xx SPI Chip Select as GPIO support"
>  	depends on PLAT_SPEAR
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 1324c8f966a7..993f8ad54a19 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -109,6 +109,7 @@ obj-$(CONFIG_GPIO_REG)		+= gpio-reg.o
>  obj-$(CONFIG_ARCH_SA1100)	+= gpio-sa1100.o
>  obj-$(CONFIG_GPIO_SCH)		+= gpio-sch.o
>  obj-$(CONFIG_GPIO_SCH311X)	+= gpio-sch311x.o
> +obj-$(CONFIG_GPIO_SNPS_CREG)	+= gpio-creg-snps.o
>  obj-$(CONFIG_GPIO_SODAVILLE)	+= gpio-sodaville.o
>  obj-$(CONFIG_GPIO_SPEAR_SPICS)	+= gpio-spear-spics.o
>  obj-$(CONFIG_GPIO_SPRD)		+= gpio-sprd.o
> diff --git a/drivers/gpio/gpio-creg-snps.c b/drivers/gpio/gpio-creg-snps.c
> new file mode 100644
> index 000000000000..2400dec529b2
> --- /dev/null
> +++ b/drivers/gpio/gpio-creg-snps.c
> @@ -0,0 +1,212 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +//
> +// Synopsys CREG (Control REGisters) GPIO driver
> +//
> +// Copyright (C) 2018 Synopsys
> +// Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> +
> +#include <linux/of.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/of_gpio.h>
> +#include <linux/io.h>
> +#include <linux/of_platform.h>
> +#include <linux/module.h>
> +
> +#include "gpiolib.h"
> +
> +#define MAX_GPIO	32
> +
> +struct creg_layout {
> +	u8 ngpio;
> +	u8 shift[MAX_GPIO];
> +	u8 on[MAX_GPIO];
> +	u8 off[MAX_GPIO];
> +	u8 bit_per_gpio[MAX_GPIO];
> +};
> +
> +struct creg_gpio {
> +	struct of_mm_gpio_chip mmchip;
> +	spinlock_t lock;
> +	const struct creg_layout *layout;
> +};
> +
> +static void creg_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct creg_gpio *hcg = gpiochip_get_data(gc);
> +	const struct creg_layout *layout = hcg->layout;
> +	u32 reg, reg_shift, value;
> +	unsigned long flags;
> +	int i;
> +
> +	value = val ? hcg->layout->on[gpio] : hcg->layout->off[gpio];
> +
> +	reg_shift = layout->shift[gpio];
> +	for (i = 0; i < gpio; i++)
> +		reg_shift += layout->bit_per_gpio[i] + layout->shift[i];
> +
> +	spin_lock_irqsave(&hcg->lock, flags);
> +	reg = readl(hcg->mmchip.regs);
> +	reg &= ~(GENMASK(layout->bit_per_gpio[i] - 1, 0) << reg_shift);
> +	reg |=  (value << reg_shift);
> +	writel(reg, hcg->mmchip.regs);
> +	spin_unlock_irqrestore(&hcg->lock, flags);
> +}
> +
> +static int creg_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	creg_gpio_set(gc, gpio, val);
> +
> +	return 0;
> +}
> +
> +static int creg_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> +{
> +	return 0; /* output */
> +}
> +
> +static int creg_gpio_xlate(struct gpio_chip *gc,
> +			   const struct of_phandle_args *gpiospec, u32 *flags)
> +{
> +	if (gpiospec->args_count != 1) {
> +		dev_err(&gc->gpiodev->dev, "invalid args_count: %d\n",
> +			gpiospec->args_count);
> +		return -EINVAL;
> +	}
> +
> +	if (gpiospec->args[0] >= gc->ngpio) {
> +		dev_err(&gc->gpiodev->dev, "gpio number is too big: %d\n",
> +			gpiospec->args[0]);
> +		return -EINVAL;
> +	}
> +
> +	return gpiospec->args[0];
> +}
> +
> +static int creg_gpio_validate_pg(struct device *dev, struct creg_gpio *hcg,
> +				 int i)
> +{
> +	const struct creg_layout *layout = hcg->layout;
> +
> +	if (layout->bit_per_gpio[i] < 1 || layout->bit_per_gpio[i] > 8)
> +		return -EINVAL;
> +
> +	/* Check that on valiue suits it's placeholder */
> +	if (GENMASK(31, layout->bit_per_gpio[i]) & layout->on[i])
> +		return -EINVAL;
> +
> +	/* Check that off valiue suits it's placeholder */
> +	if (GENMASK(31, layout->bit_per_gpio[i]) & layout->off[i])
> +		return -EINVAL;
> +
> +	if (layout->on[i] == layout->off[i])
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int creg_gpio_validate(struct device *dev, struct creg_gpio *hcg,
> +			      u32 ngpios)
> +{
> +	u32 reg_len = 0;
> +	int i;
> +
> +	if (hcg->layout->ngpio < 1 || hcg->layout->ngpio > MAX_GPIO)
> +		return -EINVAL;
> +
> +	if (ngpios < 1 || ngpios > hcg->layout->ngpio) {
> +		dev_err(dev, "ngpios must be in [1:%u]\n", hcg->layout->ngpio);
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < hcg->layout->ngpio; i++) {
> +		if (creg_gpio_validate_pg(dev, hcg, i))
> +			return -EINVAL;
> +
> +		reg_len += hcg->layout->shift[i] + hcg->layout->bit_per_gpio[i];
> +	}
> +
> +	/* Check that we suit in 32 bit register */
> +	if (reg_len > 32)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static const struct creg_layout hsdk_cs_ctl = {
> +	.ngpio		= 10,
> +	.shift		= { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
> +	.off		= { 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 },
> +	.on		= { 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 },
> +	.bit_per_gpio	= { 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 }
> +};
> +
> +static const struct creg_layout axs10x_flsh_cs_ctl = {
> +	.ngpio		= 1,
> +	.shift		= { 0 },
> +	.off		= { 1 },
> +	.on		= { 3 },
> +	.bit_per_gpio	= { 2 }
> +};
> +
> +static const struct of_device_id creg_gpio_ids[] = {
> +	{
> +		.compatible = "snps,creg-gpio-axs10x",
> +		.data = &axs10x_flsh_cs_ctl
> +	}, {
> +		.compatible = "snps,creg-gpio-hsdk",
> +		.data = &hsdk_cs_ctl
> +	}, { /* sentinel */ }
> +};
> +
> +static int creg_gpio_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *match;
> +	struct device *dev = &pdev->dev;
> +	struct creg_gpio *hcg;
> +	u32 ngpios;
> +	int ret;
> +
> +	hcg = devm_kzalloc(dev, sizeof(struct creg_gpio), GFP_KERNEL);
> +	if (!hcg)
> +		return -ENOMEM;
> +
> +	match = of_match_node(creg_gpio_ids, pdev->dev.of_node);
> +	hcg->layout = match->data;
> +	if (!hcg->layout)
> +		return -EINVAL;
> +
> +	ret = of_property_read_u32(dev->of_node, "ngpios", &ngpios);
> +	if (ret)
> +		return ret;
> +
> +	ret = creg_gpio_validate(dev, hcg, ngpios);
> +	if (ret)
> +		return ret;
> +
> +	spin_lock_init(&hcg->lock);
> +
> +	hcg->mmchip.gc.ngpio = ngpios;
> +	hcg->mmchip.gc.set = creg_gpio_set;
> +	hcg->mmchip.gc.get_direction = creg_gpio_get_direction;
> +	hcg->mmchip.gc.direction_output = creg_gpio_dir_out;
> +	hcg->mmchip.gc.of_xlate = creg_gpio_xlate;
> +	hcg->mmchip.gc.of_gpio_n_cells = 1;
> +
> +	ret = of_mm_gpiochip_add_data(pdev->dev.of_node, &hcg->mmchip, hcg);
> +	if (ret)
> +		return ret;
> +
> +	dev_info(dev, "GPIO controller with %d gpios probed\n", ngpios);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver creg_gpio_snps_driver = {
> +	.driver = {
> +		.name = "snps-creg-gpio",
> +		.of_match_table = creg_gpio_ids,
> +	},
> +	.probe  = creg_gpio_probe,
> +};
> +builtin_platform_driver(creg_gpio_snps_driver);
-- 
 Eugeniy Paltsev

Re: [PATCH v3 1/2] GPIO: add single-register GPIO via CREG driver

[Linus Walleij]

Hi Eugeniy,

sorry for the delay, the driver is different from what I'm
used to so I needed focuses attention and it took some time.

On Tue, Sep 11, 2018 at 5:09 PM Eugeniy Paltsev
<Eugeniy.Paltsev@synopsys.com> wrote:

> Add single-register MMIO GPIO driver for complex cases where
> only several fields in register belong to GPIO lines and each GPIO
> line owns a field with different length and on/off value.
>
> Such CREG GPIOs are used in Synopsys AXS10x and HSDK boards.
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
> Changes v2->v3:
>  * Move parameters into a lookup table instead of device tree.
>  * Use the ngpios attribute for instead of snps,ngpios.

This is looking good! Just a few small things I want you to fix
(we can certainly queue this for the next kernel):

> +#include <linux/of.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/of_gpio.h>

Replace this with:
#include <linux/gpio/driver.h>

Drivers should only need to include that file. (Also move away from
mm_gpio_chip as per below.)

> +#include "gpiolib.h"

Why?

> +struct creg_gpio {
> +       struct of_mm_gpio_chip mmchip;

I would prefer to move away from using this. Just create a regular driver
please. Just struct gpio_chip and add a member
void __iomem *base; instead of referring to mmchip.regs.

In fact I want to rewrite all mm_gpio_chips but I just haven't had time.

> +static void creg_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)

Please rename the variable "gpio" to "offset".

This is clearer because "gpio" becomes quite ambigous.

> +static int creg_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> +{
> +       return 0; /* output */
> +}

I think with the recent code changes in gpiolib you do not need to define
this function at all.
https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git/commit/?h=devel&id=ae9847f48a4b4bff0335da20be63ac84d94eb54c

> +static int creg_gpio_xlate(struct gpio_chip *gc,
> +                          const struct of_phandle_args *gpiospec, u32 *flags)
> +{
> +       if (gpiospec->args_count != 1) {
> +               dev_err(&gc->gpiodev->dev, "invalid args_count: %d\n",
> +                       gpiospec->args_count);
> +               return -EINVAL;
> +       }
> +
> +       if (gpiospec->args[0] >= gc->ngpio) {
> +               dev_err(&gc->gpiodev->dev, "gpio number is too big: %d\n",
> +                       gpiospec->args[0]);
> +               return -EINVAL;
> +       }
> +
> +       return gpiospec->args[0];
> +}

Another reason to not use mm_gpio_chip: just rely on standard twocell
translation and you can delete this.

> +       /* Check that we suit in 32 bit register */

s/suit/fit

Yours,
Linus Walleij

[PATCH v3 2/2] dt-bindings: Document the Synopsys GPIO via CREG bindings

[Eugeniy Paltsev]

This patch adds documentation of device tree bindings for the Synopsys
GPIO via CREG driver.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
 .../devicetree/bindings/gpio/snps,creg-gpio.txt        | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt

diff --git a/Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt b/Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt
new file mode 100644
index 000000000000..11aba2f34066
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt
@@ -0,0 +1,18 @@
+Synopsys GPIO via CREG (Control REGisters) driver
+
+Required properties:
+- compatible : "snps,creg-gpio-hsdk" or "snps,creg-gpio-axs10x".
+- reg : Exactly one register range with length 0x4.
+- #gpio-cells : Should be one - the pin number.
+- gpio-controller : Marks the device node as a GPIO controller.
+- ngpios : Number of GPIO pins.
+
+Example:
+
+gpio: gpio@f00014b0 {
+	compatible = "snps,creg-gpio-hsdk";
+	reg = <0xf00014b0 0x4>;
+	gpio-controller;
+	#gpio-cells = <1>;
+	ngpios = <2>;
+};
-- 
2.14.4

Re: [PATCH v3 2/2] dt-bindings: Document the Synopsys GPIO via CREG bindings

[Linus Walleij]

On Tue, Sep 11, 2018 at 5:09 PM Eugeniy Paltsev
<Eugeniy.Paltsev@synopsys.com> wrote:

> This patch adds documentation of device tree bindings for the Synopsys
> GPIO via CREG driver.
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

This is fine, just waiting for the final version of the driver.

Yours,
Linus Walleij

Re: [PATCH v3 2/2] dt-bindings: Document the Synopsys GPIO via CREG bindings

[Rob Herring]

On Tue, 11 Sep 2018 18:09:25 +0300, Eugeniy Paltsev wrote:
> This patch adds documentation of device tree bindings for the Synopsys
> GPIO via CREG driver.
> 
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
>  .../devicetree/bindings/gpio/snps,creg-gpio.txt        | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/snps,creg-gpio.txt
> 

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