Message-ID: <1777251.JReTVdX0Pd@avalon>
Date:	Wed, 13 Nov 2013 13:03:35 +0100
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Magnus Damm <magnus.damm@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org,
	linus.walleij@...aro.org, grant.likely@...retlab.ca,
	horms@...ge.net.au
Subject: Re: [PATCH] gpio: Renesas RZ GPIO driver

Hi Magnus,

Thank you for the patch.

Please read below for a couple of comments in addition to Linus' review.

On Thursday 07 November 2013 08:47:37 Magnus Damm wrote:
> From: Magnus Damm <damm@...nsource.se>
> 
> This patch adds a GPIO driver for the RZ series of SoCs from
> Renesas. The driver can be used as platform device with dynamic
> or static GPIO assignment or via DT using dynamic GPIOs.
> 
> The hardware allows control of GPIOs in blocks of up to 16 pins,
> and once device may span multiple blocks. Interrupts are not
> included in this hardware block, if interrupts are needed then
> the PFC needs to be configured to a IRQ pin function which is
> handled by the GIC hardware.
> 
> Tested with yet-to-be-posted platform device and DT devices on
> r7s72100 and Genmai using LEDs, DIP switches and I2C bitbang.
> 
> Signed-off-by: Magnus Damm <damm@...nsource.se>
> ---
> 
>  drivers/gpio/Kconfig                  |    6
>  drivers/gpio/Makefile                 |    1
>  drivers/gpio/gpio-rz.c                |  241 ++++++++++++++++++++++++++++++
>  include/linux/platform_data/gpio-rz.h |   13 +
>  4 files changed, 261 insertions(+)
> 
> --- 0001/drivers/gpio/Kconfig
> +++ work/drivers/gpio/Kconfig	2013-11-06 12:07:13.000000000 +0900
> @@ -230,6 +230,12 @@ config GPIO_RCAR
>  	help
>  	  Say yes here to support GPIO on Renesas R-Car SoCs.
> 
> +config GPIO_RZ
> +	tristate "Renesas RZ GPIO"
> +	depends on ARM
> +	help
> +	  Say yes here to support GPIO on Renesas RZ SoCs.
> +
>  config GPIO_SAMSUNG
>  	bool
>  	depends on PLAT_SAMSUNG
> --- 0001/drivers/gpio/Makefile
> +++ work/drivers/gpio/Makefile	2013-11-06 12:07:13.000000000 +0900
> @@ -62,6 +62,7 @@ obj-$(CONFIG_GPIO_PXA)		+= gpio-pxa.o
>  obj-$(CONFIG_GPIO_RC5T583)	+= gpio-rc5t583.o
>  obj-$(CONFIG_GPIO_RDC321X)	+= gpio-rdc321x.o
>  obj-$(CONFIG_GPIO_RCAR)		+= gpio-rcar.o
> +obj-$(CONFIG_GPIO_RZ)		+= gpio-rz.o
>  obj-$(CONFIG_GPIO_SAMSUNG)	+= gpio-samsung.o
>  obj-$(CONFIG_ARCH_SA1100)	+= gpio-sa1100.o
>  obj-$(CONFIG_GPIO_SCH)		+= gpio-sch.o
> --- /dev/null
> +++ work/drivers/gpio/gpio-rz.c	2013-11-06 14:20:02.000000000 +0900
> @@ -0,0 +1,241 @@
> +/*
> + * RZ GPIO Support - Ports
> + *
> + *  Copyright (C) 2013 Magnus Damm
> + *
> + * 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
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 
> USA
> + */

You can ditch the last two paragraphs.

> +
> +#include <linux/init.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/interrupt.h>
> +#include <linux/ioport.h>
> +#include <linux/io.h>
> +#include <linux/bitops.h>
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_data/gpio-rz.h>

Could you please sort the headers alphabetically ?

> +
> +enum { REG_PSR, REG_PPR, REG_PMSR, REG_NR };
> +
> +struct rz_gpio_priv {
> +	void __iomem *io[REG_NR];
> +	struct gpio_chip gpio_chip;
> +};
> +
> +static inline unsigned long rz_gpio_read_ppr(struct rz_gpio_priv *p, int
> offs)
> +{
> +	unsigned long msk = BIT(offs % RZ_GPIOS_PER_PORT);
> +	int offset = (offs / RZ_GPIOS_PER_PORT) * 4;

offs and offset are unsigned, you can make them unsigned int.

> +	return ioread32(p->io[REG_PPR] + offset) & msk;

I believe you should return !!(...) here, or in the caller, to make sure the 
gpio_get_value() operation returns either 0 or 1. I would do it here and 
return a u32 instead of unsigned long.

> +}
> +
> +static inline void rz_gpio_write(struct rz_gpio_priv *p, int reg, int offs,
> +				 bool value)
> +{
> +	unsigned long msk = BIT(offs % RZ_GPIOS_PER_PORT);
> +	int offset = (offs / RZ_GPIOS_PER_PORT) * 4;

offs and offset are unsigned here too.

> +
> +	/* upper 16 bits contain mask and lower 16 actual value */
> +	iowrite32(value ? (msk | (msk << 16)) : (msk << 16),

I would have written it has

(value ? msk : 0) | (msk << 16)

but I suppose gcc is smart enough to optimize this.

> +		  p->io[reg] + offset);
> +}
> +
> +static inline struct rz_gpio_priv *gpio_to_priv(struct gpio_chip *chip)
> +{
> +	return container_of(chip, struct rz_gpio_priv, gpio_chip);
> +}
> +
> +static int rz_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> +{
> +	/* Set bit in PM register via PMSR to disable output */
> +	rz_gpio_write(gpio_to_priv(chip), REG_PMSR, offset, true);
> +	return 0;
> +}
> +
> +static int rz_gpio_get(struct gpio_chip *chip, unsigned offset)
> +{
> +	/* Get bit from PPR register to determine pin state */
> +	return (int)(rz_gpio_read_ppr(gpio_to_priv(chip), offset));
> +}
> +
> +static void rz_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
> +{
> +	/* Set bit in P register via PSR to control output */
> +	rz_gpio_write(gpio_to_priv(chip), REG_PSR, offset, !!value);
> +}
> +
> +static int rz_gpio_direction_output(struct gpio_chip *chip, unsigned
> offset,
> +				   int value)
> +{
> +	/* Write GPIO value to output before selecting output mode of pin */
> +	rz_gpio_set(chip, offset, value);
> +
> +	/* Clear bit in PM register via PMSR to enable output */
> +	rz_gpio_write(gpio_to_priv(chip), REG_PMSR, offset, false);
> +	return 0;
> +}
> +
> +static int rz_gpio_request(struct gpio_chip *chip, unsigned offset)
> +{
> +	return pinctrl_request_gpio(chip->base + offset);
> +}
> +
> +static void rz_gpio_free(struct gpio_chip *chip, unsigned offset)
> +{
> +	pinctrl_free_gpio(chip->base + offset);
> +
> +	/* Set the GPIO as an input to ensure that the next GPIO request won't
> +	* drive the GPIO pin as an output.
> +	*/
> +	rz_gpio_direction_input(chip, offset);
> +}
> +
> +static int rz_gpio_probe(struct platform_device *pdev)
> +{
> +	struct gpio_rz_config *pdata = dev_get_platdata(&pdev->dev);
> +	struct rz_gpio_priv *p;
> +	struct resource *io[3];
> +	struct gpio_chip *gpio_chip;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct of_phandle_args args;
> +	int number_of_pins, gpio_base;
> +	int k, nr;

unsigned ?

By the way, what's wrong with i as a loop index ? :-)

> +	int ret;
> +
> +	p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
> +	if (!p) {
> +		dev_err(&pdev->dev, "failed to allocate driver data\n");
> +		return -ENOMEM;
> +	}
> +
> +	for (k = 0; k < REG_NR; k++)
> +		io[k] = platform_get_resource(pdev, IORESOURCE_MEM, k);
> +
> +	/* In case of 3 resources PSR, PPR and PMSR order is expected */
> +	if (io[REG_PSR] && io[REG_PPR] && io[REG_PMSR]) {
> +		nr = REG_NR;
> +	} else {
> +		/* A single resource is also acceptable (PPR only) */
> +		if (io[0] && !io[1] && !io[2]) {
> +			nr = 1;
> +		} else {
> +			dev_err(&pdev->dev, "missing IOMEM\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	for (k = 0; k < nr; k++) {
> +		p->io[k] = devm_ioremap_nocache(&pdev->dev, io[k]->start,
> +						resource_size(io[k]));

You can use devm_ioremap_resource. The function prints an error on failure so 
you can remove the dev_err() call below. Make sure to check the return value 
with IS_ERR() and return PTR_ERR() insted of the fixed -ENXIO error.

> +		if (!p->io[k]) {
> +			dev_err(&pdev->dev, "failed to remap low I/O memory\n");
> +			return -ENXIO;
> +		}
> +	}
> +
> +	/* If only 1 resource is available it must be PPR */
> +	if (nr == 1) {
> +		io[REG_PPR] = io[0];
> +		p->io[REG_PPR] = p->io[0];
> +		io[0] = NULL;
> +		p->io[0] = NULL;
> +	}
> +
> +	/* Support one device spanning several ports */
> +	number_of_pins = RZ_GPIOS_PER_PORT;
> +	if (io[REG_PSR])
> +		number_of_pins *= resource_size(io[REG_PSR]) / 4;
> +
> +	gpio_base = pdata ? pdata->gpio_base : -1;
> +
> +	if (IS_ENABLED(CONFIG_OF) && np) {
> +		ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3, 0,
> +						       &args);
> +		number_of_pins = ret == 0 ? args.args[2] : RZ_GPIOS_PER_PORT;
> +	}
> +
> +	gpio_chip = &p->gpio_chip;
> +	gpio_chip->direction_input = rz_gpio_direction_input;
> +	gpio_chip->get = rz_gpio_get;
> +	gpio_chip->direction_output = rz_gpio_direction_output;
> +	gpio_chip->set = rz_gpio_set;
> +	gpio_chip->request = rz_gpio_request;
> +	gpio_chip->free = rz_gpio_free;
> +	gpio_chip->label = dev_name(&pdev->dev);
> +	gpio_chip->dev = &pdev->dev;
> +	gpio_chip->owner = THIS_MODULE;
> +	gpio_chip->base = gpio_base;
> +	gpio_chip->ngpio = number_of_pins;
> +
> +	ret = gpiochip_add(gpio_chip);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to add GPIO controller\n");
> +		return ret;
> +	}
> +
> +	dev_info(&pdev->dev, "driving %d GPIOs\n", number_of_pins);
> +
> +	if (pdata && pdata->pctl_name) {
> +		ret = gpiochip_add_pin_range(gpio_chip, pdata->pctl_name, 0,
> +					     gpio_chip->base, gpio_chip->ngpio);
> +		if (ret < 0)
> +			dev_warn(&pdev->dev, "failed to add pin range\n");
> +	}
> +	return 0;
> +}
> +
> +static int rz_gpio_remove(struct platform_device *pdev)
> +{
> +	struct rz_gpio_priv *p = platform_get_drvdata(pdev);
> +
> +	return gpiochip_remove(&p->gpio_chip);
> +}
> +
> +static const struct of_device_id rz_gpio_dt_ids[] = {
> +	{ .compatible = "renesas,gpio-rz", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, rz_gpio_dt_ids);
> +
> +static struct platform_driver rz_gpio_device_driver = {
> +	.probe		= rz_gpio_probe,
> +	.remove		= rz_gpio_remove,
> +	.driver		= {
> +		.name	= "gpio_rz",
> +		.of_match_table = rz_gpio_dt_ids,
> +		.owner		= THIS_MODULE,
> +	}
> +};
> +
> +static int __init rz_gpio_init(void)
> +{
> +	return platform_driver_register(&rz_gpio_device_driver);
> +}
> +postcore_initcall(rz_gpio_init);
> +
> +static void __exit rz_gpio_exit(void)
> +{
> +	platform_driver_unregister(&rz_gpio_device_driver);
> +}
> +module_exit(rz_gpio_exit);
> +
> +MODULE_AUTHOR("Magnus Damm");
> +MODULE_DESCRIPTION("Renesas RZ Port GPIO Driver");
> +MODULE_LICENSE("GPL v2");
> --- /dev/null
> +++ work/include/linux/platform_data/gpio-rz.h	2013-11-06 
14:18:46.000000000
> +0900 @@ -0,0 +1,13 @@
> +#ifndef __GPIO_RZ_H__
> +#define __GPIO_RZ_H__
> +
> +struct gpio_rz_config {
> +	int gpio_base;
> +	const char *pctl_name;
> +};
> +
> +#define RZ_GPIOS_PER_PORT 16
> +
> +#define RZ_PORT_PIN(bank, pin)	(((bank) * RZ_GPIOS_PER_PORT) + (pin))
> +
> +#endif /* __GPIO_RZ_H__ */
-- 
Regards,

Laurent Pinchart

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