Re: [PATCH v2] gpio: Renesas RZ GPIO driver V2

From: Laurent Pinchart
Date: Wed Nov 13 2013 - 18:50:20 EST


Hi Magnus,

On Thursday 14 November 2013 08:34:11 Magnus Damm wrote:
> From: Magnus Damm <damm@xxxxxxxxxxxxx>
>
> This patch adds a GPIO driver for the RZ series of SoCs from
> Renesas. The V2 of the driver requires DT to be used.
>
> The hardware allows control of GPIOs in blocks of up to 16 pins.
> 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 DT devices on r7s72100 and Genmai using
> LEDs, DIP switches and I2C bitbang.
>
> Signed-off-by: Magnus Damm <damm@xxxxxxxxxxxxx>
> ---
>
> Changes since V1:
> - Drop platform data interface as suggested by Linus Walleij, thanks!
> - Various changes suggested by Laurent Pinchart (except !!), thanks!

And most unsigned types :-)

> drivers/gpio/Kconfig | 6 +
> drivers/gpio/Makefile | 1
> drivers/gpio/gpio-rz.c | 213 +++++++++++++++++++++++++++++++++++++++++++++

I've failed to notice it, but you're missing DT bindings documentation.

> 3 files changed, 220 insertions(+)
>
> --- 0001/drivers/gpio/Kconfig
> +++ work/drivers/gpio/Kconfig 2013-11-14 08:08:55.000000000 +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 2013-11-14 08:08:55.000000000 +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 2013-11-14 08:24:48.000000000 +0900
> @@ -0,0 +1,213 @@
> +/*
> + * 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
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +#define RZ_GPIOS_PER_PORT 16
> +
> +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 u32 rz_gpio_read_ppr(struct rz_gpio_priv *p, int offs)
> +{
> + unsigned long msk = BIT(offs % RZ_GPIOS_PER_PORT);
> + unsigned int offset = (offs / RZ_GPIOS_PER_PORT) * 4;
> +
> + return ioread32(p->io[REG_PPR] + offset) & msk;
> +}
> +
> +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);
> + unsigned int offset = (offs / RZ_GPIOS_PER_PORT) * 4;
> +
> + /* upper 16 bits contain mask and lower 16 actual value */
> + iowrite32(value ? (msk | (msk << 16)) : (msk << 16),
> + 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));

No neeed for an explicit cast to int.

I stand behind my original comment, shouldn't the get operation return 0 or 1
? The implementation will return 0 or (1 << GPIO bit position). Linus, what's
the GPIO API contract on this ?

> +}
> +
> +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 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;
> + unsigned int number_of_pins;
> + int k, nr;

I still don't userstand 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_resource(&pdev->dev, io[k]);
> + if (IS_ERR(p->io[k]))
> + return PTR_ERR(p->io[k]);
> + }
> +
> + /* 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;
> + }
> +
> + ret = np ? of_parse_phandle_with_fixed_args(np, "gpio-ranges",
> + 3, 0, &args) : -1;

I don't think np can be NULL.

> + number_of_pins = ret == 0 ? args.args[2] : RZ_GPIOS_PER_PORT;

Shouldn't the gpio-ranges property be mandatory ?

> +
> + 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 = -1;
> + 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);
> + 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");
--
Regards,

Laurent Pinchart

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