Re: [PATCH v2 2/2] gpio: Add Cadence GPIO driver

[Bartosz Golaszewski]

pon., 17 gru 2018 o 16:37 Jan Kotas <jank@xxxxxxxxxxx> napisaÅ(a):
>
> This patch adds a driver for Cadence GPIO controller.
>
> It can be enabled with GPIO_CADENCE Kconfig option.
> It uses generic GPIO infrastructure and works
> as an interrupt controller.
> At the moment it only supports level sensitive irqs.
>
> Signed-off-by: Jan Kotas <jank@xxxxxxxxxxx>
> ---
>  drivers/gpio/Kconfig        |   8 ++
>  drivers/gpio/Makefile       |   1 +
>  drivers/gpio/gpio-cadence.c | 275 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 284 insertions(+)
>  create mode 100644 drivers/gpio/gpio-cadence.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 833a1b51c..8259f8f25 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -160,6 +160,14 @@ config GPIO_BRCMSTB
>         help
>           Say yes here to enable GPIO support for Broadcom STB (BCM7XXX) SoCs.
>
> +config GPIO_CADENCE
> +       tristate "Cadence GPIO support"
> +       depends on OF_GPIO
> +       select GPIO_GENERIC
> +       select GPIOLIB_IRQCHIP
> +       help
> +         Say yes here to enable support for Cadence GPIO controller.
> +
>  config GPIO_CLPS711X
>         tristate "CLPS711X GPIO support"
>         depends on ARCH_CLPS711X || COMPILE_TEST
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 671c4477c..5fce8634a 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_GPIO_BCM_KONA)   += gpio-bcm-kona.o
>  obj-$(CONFIG_GPIO_BD9571MWV)   += gpio-bd9571mwv.o
>  obj-$(CONFIG_GPIO_BRCMSTB)     += gpio-brcmstb.o
>  obj-$(CONFIG_GPIO_BT8XX)       += gpio-bt8xx.o
> +obj-$(CONFIG_GPIO_CADENCE)     += gpio-cadence.o
>  obj-$(CONFIG_GPIO_CLPS711X)    += gpio-clps711x.o
>  obj-$(CONFIG_GPIO_CS5535)      += gpio-cs5535.o
>  obj-$(CONFIG_GPIO_CRYSTAL_COVE)        += gpio-crystalcove.o
> diff --git a/drivers/gpio/gpio-cadence.c b/drivers/gpio/gpio-cadence.c
> new file mode 100644
> index 000000000..16cc9f50f
> --- /dev/null
> +++ b/drivers/gpio/gpio-cadence.c
> @@ -0,0 +1,275 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Copyright 2017-2018 Cadence
> + *
> + * Authors:
> + *  Jan Kotas <jank@xxxxxxxxxxx>
> + *  Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/gpio/driver.h>
> +#include <linux/clk.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define CDNS_GPIO_BYPASS_MODE          0x00
> +#define CDNS_GPIO_DIRECTION_MODE       0x04
> +#define CDNS_GPIO_OUTPUT_EN            0x08
> +#define CDNS_GPIO_OUTPUT_VALUE         0x0c
> +#define CDNS_GPIO_INPUT_VALUE          0x10
> +#define CDNS_GPIO_IRQ_MASK             0x14
> +#define CDNS_GPIO_IRQ_EN               0x18
> +#define CDNS_GPIO_IRQ_DIS              0x1c
> +#define CDNS_GPIO_IRQ_STATUS           0x20
> +#define CDNS_GPIO_IRQ_TYPE             0x24
> +#define CDNS_GPIO_IRQ_VALUE            0x28
> +#define CDNS_GPIO_IRQ_ANY_EDGE         0x2c
> +
> +struct cdns_gpio_chip {
> +       struct gpio_chip gc;
> +       struct clk *pclk;
> +       void __iomem *regs;
> +       u32 bypass_orig;
> +};
> +
> +static int cdns_gpio_request(struct gpio_chip *chip, unsigned int offset)
> +{
> +       struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
> +
> +       iowrite32(ioread32(cgpio->regs + CDNS_GPIO_BYPASS_MODE) & ~BIT(offset),
> +                 cgpio->regs + CDNS_GPIO_BYPASS_MODE);
> +
> +       return 0;
> +}
> +
> +static void cdns_gpio_free(struct gpio_chip *chip, unsigned int offset)
> +{
> +       struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
> +
> +       iowrite32(ioread32(cgpio->regs + CDNS_GPIO_BYPASS_MODE) |
> +                 (BIT(offset) & cgpio->bypass_orig),
> +                 cgpio->regs + CDNS_GPIO_BYPASS_MODE);
> +}
> +
> +static void cdns_gpio_irq_mask(struct irq_data *d)
> +{
> +       struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
> +       struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
> +
> +       iowrite32(BIT(d->hwirq), cgpio->regs + CDNS_GPIO_IRQ_DIS);
> +}
> +
> +static void cdns_gpio_irq_unmask(struct irq_data *d)
> +{
> +       struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
> +       struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
> +
> +       iowrite32(BIT(d->hwirq), cgpio->regs + CDNS_GPIO_IRQ_EN);
> +}
> +
> +static int cdns_gpio_irq_set_type(struct irq_data *d, unsigned int type)
> +{
> +       struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
> +       struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
> +       u32 int_value = ioread32(cgpio->regs + CDNS_GPIO_IRQ_VALUE);
> +       u32 int_type = ioread32(cgpio->regs + CDNS_GPIO_IRQ_TYPE);
> +       u32 mask = BIT(d->hwirq);
> +
> +       int_value &= ~mask;
> +       int_type &= ~mask;
> +
> +       /*
> +        * The GPIO controller doesn't have an ACK register.
> +        * All interrupt statuses are cleared on a status register read.
> +        * Don't support edge interrupts for now.
> +        */
> +
> +       if (type == IRQ_TYPE_LEVEL_HIGH) {
> +               int_type |= mask;
> +               int_value |= mask;
> +       } else if (type == IRQ_TYPE_LEVEL_LOW) {
> +               int_type |= mask;
> +       } else {
> +               return -EINVAL;
> +       }
> +
> +       iowrite32(int_value, cgpio->regs + CDNS_GPIO_IRQ_VALUE);
> +       iowrite32(int_type, cgpio->regs + CDNS_GPIO_IRQ_TYPE);
> +
> +       return 0;
> +}
> +
> +static void cdns_gpio_irq_handler(struct irq_desc *desc)
> +{
> +       struct gpio_chip *chip = irq_desc_get_handler_data(desc);
> +       struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
> +       struct irq_chip *irqchip = irq_desc_get_chip(desc);
> +       unsigned long status;
> +       int hwirq;
> +
> +       chained_irq_enter(irqchip, desc);
> +
> +       status = ioread32(cgpio->regs + CDNS_GPIO_IRQ_STATUS) &
> +               ~ioread32(cgpio->regs + CDNS_GPIO_IRQ_MASK);
> +
> +       for_each_set_bit(hwirq, &status, chip->ngpio)
> +               generic_handle_irq(irq_find_mapping(chip->irq.domain, hwirq));
> +
> +       chained_irq_exit(irqchip, desc);
> +}
> +
> +static struct irq_chip cdns_gpio_irqchip = {
> +       .name           = "cdns-gpio",
> +       .irq_mask       = cdns_gpio_irq_mask,
> +       .irq_unmask     = cdns_gpio_irq_unmask,
> +       .irq_set_type   = cdns_gpio_irq_set_type
> +};
> +
> +static int cdns_gpio_probe(struct platform_device *pdev)
> +{
> +       struct cdns_gpio_chip *cgpio;
> +       struct resource *res;
> +       int ret, irq;
> +       u32 dir_prev;
> +       u32 num_gpios = 32;
> +
> +       cgpio = devm_kzalloc(&pdev->dev, sizeof(*cgpio), GFP_KERNEL);
> +       if (!cgpio)
> +               return -ENOMEM;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       cgpio->regs = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(cgpio->regs))
> +               return PTR_ERR(cgpio->regs);
> +
> +       of_property_read_u32(pdev->dev.of_node, "ngpios", &num_gpios);
> +
> +       if (num_gpios > 32) {
> +               dev_err(&pdev->dev, "ngpios must be less or equal 32\n");
> +               return -EINVAL;
> +       }
> +
> +       /*
> +        * Set all pins as inputs by default, otherwise:
> +        * gpiochip_lock_as_irq:
> +        * tried to flag a GPIO set as output for IRQ
> +        * Generic GPIO driver stores the direction value internally,
> +        * so it needs to be changed before bgpio_init() is called.
> +        */
> +       dir_prev = ioread32(cgpio->regs + CDNS_GPIO_DIRECTION_MODE);
> +       iowrite32(GENMASK(num_gpios - 1, 0),
> +                 cgpio->regs + CDNS_GPIO_DIRECTION_MODE);
> +
> +       ret = bgpio_init(&cgpio->gc, &pdev->dev, 4,
> +                        cgpio->regs + CDNS_GPIO_INPUT_VALUE,
> +                        cgpio->regs + CDNS_GPIO_OUTPUT_VALUE,
> +                        NULL,
> +                        NULL,
> +                        cgpio->regs + CDNS_GPIO_DIRECTION_MODE,
> +                        BGPIOF_READ_OUTPUT_REG_SET);
> +       if (ret) {
> +               dev_err(&pdev->dev, "Failed to register generic gpio, %d\n",
> +                       ret);
> +               goto err_revert_dir;
> +       }
> +
> +       cgpio->gc.label = dev_name(&pdev->dev);
> +       cgpio->gc.ngpio = num_gpios;
> +       cgpio->gc.parent = &pdev->dev;
> +       cgpio->gc.base = -1;
> +       cgpio->gc.owner = THIS_MODULE;
> +       cgpio->gc.request = cdns_gpio_request;
> +       cgpio->gc.free = cdns_gpio_free;
> +
> +       cgpio->pclk = devm_clk_get(&pdev->dev, NULL);
> +       if (IS_ERR(cgpio->pclk)) {
> +               ret = PTR_ERR(cgpio->pclk);
> +               dev_err(&pdev->dev,
> +                       "Failed to retrieve peripheral clock, %d\n", ret);
> +               goto err_revert_dir;
> +       }
> +
> +       ret = clk_prepare_enable(cgpio->pclk);
> +       if (ret) {
> +               dev_err(&pdev->dev,
> +                       "Failed to enable the peripheral clock, %d\n", ret);
> +               goto err_revert_dir;
> +       }
> +
> +       ret = devm_gpiochip_add_data(&pdev->dev, &cgpio->gc, cgpio);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "Could not register gpiochip, %d\n", ret);
> +               goto err_disable_clk;
> +       }
> +
> +       /*
> +        * irq_chip support
> +        */
> +       irq = platform_get_irq(pdev, 0);
> +       if (irq >= 0) {
> +               ret = gpiochip_irqchip_add(&cgpio->gc, &cdns_gpio_irqchip,
> +                                          0, handle_level_irq,
> +                                          IRQ_TYPE_NONE);
> +               if (ret) {
> +                       dev_err(&pdev->dev, "Could not add irqchip, %d\n",
> +                               ret);
> +                       goto err_disable_clk;
> +               }
> +               gpiochip_set_chained_irqchip(&cgpio->gc, &cdns_gpio_irqchip,
> +                                            irq, cdns_gpio_irq_handler);
> +       }
> +
> +       cgpio->bypass_orig = ioread32(cgpio->regs + CDNS_GPIO_BYPASS_MODE);
> +
> +       /*
> +        * Enable gpio outputs, ignored for input direction
> +        */
> +       iowrite32(GENMASK(num_gpios - 1, 0),
> +                 cgpio->regs + CDNS_GPIO_OUTPUT_EN);
> +       iowrite32(0, cgpio->regs + CDNS_GPIO_BYPASS_MODE);
> +
> +       platform_set_drvdata(pdev, cgpio);
> +       return 0;
> +
> +err_disable_clk:
> +       clk_disable_unprepare(cgpio->pclk);
> +
> +err_revert_dir:
> +       iowrite32(dir_prev, cgpio->regs + CDNS_GPIO_DIRECTION_MODE);
> +
> +       return ret;
> +}
> +
> +static int cdns_gpio_remove(struct platform_device *pdev)
> +{
> +       struct cdns_gpio_chip *cgpio = platform_get_drvdata(pdev);
> +
> +       iowrite32(cgpio->bypass_orig, cgpio->regs + CDNS_GPIO_BYPASS_MODE);
> +       clk_disable_unprepare(cgpio->pclk);
> +
> +       return 0;
> +}
> +
> +static const struct of_device_id cdns_of_ids[] = {
> +       { .compatible = "cdns,gpio-r1p02" },
> +       { /* sentinel */ },
> +};
> +
> +static struct platform_driver cdns_gpio_driver = {
> +       .driver = {
> +               .name = "cdns-gpio",
> +               .of_match_table = cdns_of_ids,
> +       },
> +       .probe = cdns_gpio_probe,
> +       .remove = cdns_gpio_remove,
> +};
> +module_platform_driver(cdns_gpio_driver);
> +
> +MODULE_AUTHOR("Jan Kotas <jank@xxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Cadence GPIO driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:cdns-gpio");
> --
> 2.15.0
>

The driver looks good but is there any particular reason not to use
regmap for register IO?

Bart