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Date:   Tue, 19 Oct 2021 16:50:22 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Santosh Kumar Yadav <santoshkumar.yadav@...co.com>,
        santoshyadav30@...il.com
Cc:     Peter Korsgaard <peter@...sgaard.com>,
        Mark Gross <mgross@...ux.intel.com>,
        Peter Korsgaard <peter.korsgaard@...co.com>,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH] platform/x86: Support for EC-connected GPIOs for identify
 LED/button on Barco P50 board

Hi,

On 10/13/21 16:03, Santosh Kumar Yadav wrote:
> Add a driver providing access to the GPIOs for the identify button and led
> present on Barco P50 board, based on the pcengines-apuv2.c driver.
> 
> There is unfortunately no suitable ACPI entry for the EC communication
> interface, so instead bind to boards with "P50" as their DMI product family
> and hard code the I/O port number (0x299).
> 
> The driver also hooks up the leds-gpio and gpio-keys-polled drivers to the
> GPIOs, so they are finally exposed as:
> 
> LED:
> /sys/class/leds/identify
> 
> Button: (/proc/bus/input/devices)
> I: Bus=0019 Vendor=0001 Product=0001 Version=0100
> N: Name="identify"
> P: Phys=gpio-keys-polled/input0
> S: Sysfs=/devices/platform/barco-p50-gpio/gpio-keys-polled/input/input10
> U: Uniq=
> H: Handlers=event10
> B: PROP=0
> B: EV=3
> B: KEY=1000000 0 0 0 0 0 0
> 
> Signed-off-by: Santosh Kumar Yadav <santoshkumar.yadav@...co.com>
> Signed-off-by: Peter Korsgaard <peter@...sgaard.com>

Thanks, overall this looks pretty good. I've a couple of comments inline,
please send a v2 addresing this.



> ---
>  MAINTAINERS                           |   6 +
>  drivers/platform/x86/Kconfig          |  10 +
>  drivers/platform/x86/Makefile         |   3 +
>  drivers/platform/x86/barco-p50-gpio.c | 427 ++++++++++++++++++++++++++
>  4 files changed, 446 insertions(+)
>  create mode 100644 drivers/platform/x86/barco-p50-gpio.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a4a0c2baaf27..604f544a9e17 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3220,6 +3220,12 @@ F:       drivers/video/backlight/
>  F:     include/linux/backlight.h
>  F:     include/linux/pwm_backlight.h
> 
> +BARCO P50 GPIO DRIVER
> +M:     Santosh Kumar Yadav <santoshkumar.yadav@...co.com>
> +M:     Peter Korsgaard <peter.korsgaard@...co.com>
> +S:     Maintained
> +F:     drivers/platform/x86/barco-p50-gpio.c
> +
>  BATMAN ADVANCED
>  M:     Marek Lindner <mareklindner@...mailbox.ch>
>  M:     Simon Wunderlich <sw@...onwunderlich.de>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index e21ea3d23e6f..42b4895e4acc 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -713,6 +713,16 @@ config PCENGINES_APU2
>           To compile this driver as a module, choose M here: the module
>           will be called pcengines-apuv2.
> 
> +config BARCO_P50_GPIO
> +       tristate "Barco P50 GPIO driver for identify LED/button"
> +       depends on GPIOLIB
> +       help
> +         This driver provides access to the GPIOs for the identify button
> +         and led present on Barco P50 board.
> +
> +         To compile this driver as a module, choose M here: the module
> +         will be called barco-p50-gpio.
> +
>  config SAMSUNG_LAPTOP
>         tristate "Samsung Laptop driver"
>         depends on RFKILL || RFKILL = n
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 69690e26bb6d..e1acfc03301f 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -80,6 +80,9 @@ obj-$(CONFIG_XO1_RFKILL)      += xo1-rfkill.o
>  # PC Engines
>  obj-$(CONFIG_PCENGINES_APU2)   += pcengines-apuv2.o
> 
> +# Barco
> +obj-$(CONFIG_BARCO_P50_GPIO)    += barco-p50-gpio.o
> +
>  # Samsung
>  obj-$(CONFIG_SAMSUNG_LAPTOP)   += samsung-laptop.o
>  obj-$(CONFIG_SAMSUNG_Q10)      += samsung-q10.o
> diff --git a/drivers/platform/x86/barco-p50-gpio.c b/drivers/platform/x86/barco-p50-gpio.c
> new file mode 100644
> index 000000000000..1629cfbb85db
> --- /dev/null
> +++ b/drivers/platform/x86/barco-p50-gpio.c
> @@ -0,0 +1,427 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +/*
> + * Support for EC-connected GPIOs for identify
> + * LED/button on Barco P50 board
> + *
> + * Copyright (C) 2021 Barco NV
> + * Author: Santosh Kumar Yadav <santoshkumar.yadav@...co.com>
> + */
> +
> +#define pr_fmt(fmt)    KBUILD_MODNAME ": " fmt
> +
> +#include <linux/io.h>
> +#include <linux/delay.h>
> +#include <linux/dmi.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/gpio_keys.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/gpio/machine.h>
> +#include <linux/input.h>
> +
> +
> +#define DRIVER_NAME    "barco-p50-gpio"
> +
> +/* GPIO lines */
> +#define P50_GPIO_LINE_LED      0
> +#define P50_GPIO_LINE_BTN      1
> +
> +/* GPIO IO Ports */
> +#define P50_GPIO_IO_PORT_BASE  0x299
> +
> +#define P50_PORT_DATA  0x00
> +#define P50_PORT_CMD   0x01
> +
> +#define P50_STATUS_OBF 0x01 /* EC output buffer full */
> +#define P50_STATUS_IBF 0x02 /* EC input buffer full */
> +
> +#define P50_CMD_READ   0xa0
> +#define P50_CMD_WRITE  0x50
> +
> +/* EC mailbox registers */
> +#define P50_MBOX_REG_CMD       0x00
> +#define P50_MBOX_REG_STATUS    0x01
> +#define P50_MBOX_REG_PARAM     0x02
> +#define P50_MBOX_REG_DATA      0x03
> +
> +#define P50_MBOX_CMD_READ_GPIO 0x11
> +#define P50_MBOX_CMD_WRITE_GPIO        0x12
> +#define P50_MBOX_CMD_CLEAR     0xff
> +
> +#define P50_MBOX_STATUS_SUCCESS        0x01
> +
> +#define P50_MBOX_PARAM_LED     0x12
> +#define P50_MBOX_PARAM_BTN     0x13
> +
> +
> +struct p50_gpio {
> +       struct gpio_chip gc;
> +       struct mutex lock;
> +       unsigned long base;
> +       struct platform_device *leds_pdev;
> +       struct platform_device *keys_pdev;
> +};
> +
> +static struct platform_device *gpio_pdev;
> +
> +static int gpio_params[] = {
> +       [P50_GPIO_LINE_LED] = P50_MBOX_PARAM_LED,
> +       [P50_GPIO_LINE_BTN] = P50_MBOX_PARAM_BTN,
> +};
> +
> +static const char * const gpio_names[] = {
> +       [P50_GPIO_LINE_LED] = "identify-led",
> +       [P50_GPIO_LINE_BTN] = "identify-button",
> +};
> +
> +
> +static struct gpiod_lookup_table p50_gpio_led_table = {
> +       .dev_id = "leds-gpio",
> +       .table = {
> +               GPIO_LOOKUP_IDX(DRIVER_NAME, P50_GPIO_LINE_LED, NULL, 0, GPIO_ACTIVE_HIGH),
> +               {}
> +       }
> +};
> +
> +
> +/* low level access routines */
> +
> +static int p50_wait_ec(struct p50_gpio *p50, int mask, int expected)
> +{
> +       int i, val;
> +
> +       for (i = 0; i < 100; i++) {
> +               val = inb(p50->base + P50_PORT_CMD) & mask;
> +               if (val == expected)
> +                       return 0;
> +               usleep_range(500, 2000);
> +       }
> +
> +       dev_err(p50->gc.parent, "Timed out waiting for EC (0x%x)\n", val);
> +       return -ETIMEDOUT;
> +}
> +
> +
> +static int p50_read_mbox_reg(struct p50_gpio *p50, int reg)
> +{
> +       int ret;
> +
> +       ret = p50_wait_ec(p50, P50_STATUS_IBF, 0);
> +       if (ret)
> +               return ret;
> +
> +       /* clear output buffer flag, prevent unfinished commands */
> +       inb(p50->base + P50_PORT_DATA);
> +
> +       /* cmd/address */
> +       outb(P50_CMD_READ | reg, p50->base + P50_PORT_CMD);
> +
> +       ret = p50_wait_ec(p50, P50_STATUS_OBF, P50_STATUS_OBF);
> +       if (ret)
> +               return ret;
> +
> +       return inb(p50->base + P50_PORT_DATA);
> +}
> +
> +static int p50_write_mbox_reg(struct p50_gpio *p50, int reg, int val)
> +{
> +       int ret;
> +
> +       ret = p50_wait_ec(p50, P50_STATUS_IBF, 0);
> +       if (ret)
> +               return ret;
> +
> +       /* cmd/address */
> +       outb(P50_CMD_WRITE | reg, p50->base + P50_PORT_CMD);
> +
> +       ret = p50_wait_ec(p50, P50_STATUS_IBF, 0);
> +       if (ret)
> +               return ret;
> +
> +       /* data */
> +       outb(val, p50->base + P50_PORT_DATA);
> +
> +       return 0;
> +}
> +
> +
> +/* mbox routines */
> +
> +static int p50_wait_mbox_idle(struct p50_gpio *p50)
> +{
> +       int i, val;
> +
> +       for (i = 0; i < 1000; i++) {
> +               val = p50_read_mbox_reg(p50, P50_MBOX_REG_CMD);
> +               /* cmd is 0 when idle */
> +               if (val <= 0)
> +                       return val;
> +
> +               usleep_range(500, 2000);
> +       }
> +
> +       dev_err(p50->gc.parent, "Timed out waiting for EC mbox idle (CMD: 0x%x)\n", val);
> +
> +       return -ETIMEDOUT;
> +}
> +
> +static int p50_send_mbox_cmd(struct p50_gpio *p50, int cmd, int param, int data)
> +{
> +       int ret;
> +
> +       ret = p50_wait_mbox_idle(p50);
> +       if (ret)
> +               return ret;
> +
> +       ret = p50_write_mbox_reg(p50, P50_MBOX_REG_DATA, data);
> +       if (ret)
> +               return ret;
> +
> +       ret = p50_write_mbox_reg(p50, P50_MBOX_REG_PARAM, param);
> +       if (ret)
> +               return ret;
> +
> +       ret = p50_write_mbox_reg(p50, P50_MBOX_REG_CMD, cmd);
> +       if (ret)
> +               return ret;
> +
> +       ret = p50_wait_mbox_idle(p50);
> +       if (ret)
> +               return ret;
> +
> +       ret = p50_read_mbox_reg(p50, P50_MBOX_REG_STATUS);
> +       if (ret < 0)
> +               return ret;
> +
> +       if (ret == P50_MBOX_STATUS_SUCCESS)
> +               return 0;
> +
> +       dev_err(p50->gc.parent, "Mbox command failed (CMD=0x%x STAT=0x%x PARAM=0x%x DATA=0x%x)\n",
> +               cmd, ret, param, data);
> +
> +       return -EIO;
> +}
> +
> +
> +/* gpio routines */
> +
> +static int p50_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> +{
> +       switch (offset) {
> +       case P50_GPIO_LINE_BTN:
> +               return GPIO_LINE_DIRECTION_IN;
> +
> +       case P50_GPIO_LINE_LED:
> +               return GPIO_LINE_DIRECTION_OUT;
> +
> +       default:
> +               return -EINVAL;
> +       }
> +}
> +
> +static int p50_gpio_get(struct gpio_chip *gc, unsigned int offset)
> +{
> +       struct p50_gpio *p50 = gpiochip_get_data(gc);
> +       int ret;
> +
> +       mutex_lock(&p50->lock);
> +
> +       ret = p50_send_mbox_cmd(p50, P50_MBOX_CMD_READ_GPIO, gpio_params[offset], 0);
> +       if (ret == 0)
> +               ret = p50_read_mbox_reg(p50, P50_MBOX_REG_DATA);
> +
> +       mutex_unlock(&p50->lock);
> +
> +       return ret;
> +}
> +
> +static void p50_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
> +{
> +       struct p50_gpio *p50 = gpiochip_get_data(gc);
> +
> +       mutex_lock(&p50->lock);
> +
> +       p50_send_mbox_cmd(p50, P50_MBOX_CMD_WRITE_GPIO, gpio_params[offset], value);
> +
> +       mutex_unlock(&p50->lock);
> +}
> +
> +static int p50_gpio_probe(struct platform_device *pdev)
> +{
> +       /* GPIO LEDs */
> +       struct gpio_led leds[] = {
> +               { .name = "identify" }
> +       };
> +
> +       struct gpio_led_platform_data leds_pdata = {
> +               .num_leds = ARRAY_SIZE(leds),
> +               .leds = leds,
> +       };
> +
> +       /* GPIO keyboard */
> +       struct gpio_keys_button buttons[] = {
> +               {
> +                       .code = KEY_RESTART,
> +                       .gpio = P50_GPIO_LINE_BTN,
> +                       .active_low = 1,
> +                       .type = EV_KEY,
> +                       .value = 1,
> +               },
> +       };
> +
> +       struct gpio_keys_platform_data keys_pdata = {
> +               .buttons = buttons,
> +               .nbuttons = ARRAY_SIZE(buttons),
> +               .poll_interval = 100,
> +               .rep = 0,
> +               .name = "identify",
> +       };
> +
> +       struct p50_gpio *p50;
> +       struct resource *res;
> +       int ret;
> +
> +       p50 = devm_kzalloc(&pdev->dev, sizeof(*p50), GFP_KERNEL);
> +       if (!p50)
> +               return -ENOMEM;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_IO, 0);
> +       if (!res) {
> +               dev_err(&pdev->dev, "Cannot get I/O ports\n");
> +               return -ENODEV;
> +       }
> +
> +       if (!devm_request_region(&pdev->dev, res->start, resource_size(res), pdev->name)) {
> +               dev_err(&pdev->dev, "Unable to reserve I/O region\n");
> +               return -EBUSY;
> +       }
> +
> +       p50->base = res->start;
> +
> +       ret = p50_send_mbox_cmd(p50, P50_MBOX_CMD_CLEAR, 0, 0);
> +       if (ret < 0)
> +               return -ENODEV;
> +
> +       p50->gc.owner = THIS_MODULE;
> +       p50->gc.parent = &pdev->dev;
> +       p50->gc.label = dev_name(&pdev->dev);
> +       p50->gc.ngpio = ARRAY_SIZE(gpio_names);
> +       p50->gc.names = gpio_names;
> +       p50->gc.can_sleep = true;
> +       p50->gc.base = -1;
> +       p50->gc.get_direction = p50_gpio_get_direction;
> +       p50->gc.get = p50_gpio_get;
> +       p50->gc.set = p50_gpio_set;
> +
> +       mutex_init(&p50->lock);
> +
> +       platform_set_drvdata(pdev, p50);
> +
> +       ret = devm_gpiochip_add_data(&pdev->dev, &p50->gc, p50);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "Could not register gpiochip: %d\n", ret);
> +               return ret;
> +       }
> +
> +       gpiod_add_lookup_table(&p50_gpio_led_table);
> +
> +       p50->leds_pdev = platform_device_register_data(&pdev->dev,
> +               "leds-gpio", PLATFORM_DEVID_NONE, &leds_pdata, sizeof(leds_pdata));
> +
> +       if (IS_ERR(p50->leds_pdev)) {
> +               ret = PTR_ERR(p50->leds_pdev);
> +               dev_err(&pdev->dev, "Could not register leds-gpio: %d\n", ret);
> +               goto err_leds;
> +       }
> +
> +       /* gpio-keys-polled uses old-style gpio interface, pass the right identifier */
> +       buttons[0].gpio += p50->gc.base;
> +
> +       p50->keys_pdev =
> +               platform_device_register_data(&pdev->dev, "gpio-keys-polled",
> +                                             PLATFORM_DEVID_NONE,
> +                                             &keys_pdata, sizeof(keys_pdata));
> +
> +       if (IS_ERR(p50->keys_pdev)) {
> +               ret = PTR_ERR(p50->keys_pdev);
> +               dev_err(&pdev->dev, "Could not register gpio-keys-polled: %d\n", ret);
> +               goto err_keys;
> +       }
> +
> +       return 0;
> +
> +err_keys:
> +       platform_device_unregister(p50->leds_pdev);
> +err_leds:
> +       gpiod_remove_lookup_table(&p50_gpio_led_table);
> +
> +       return ret;
> +}
> +
> +static int p50_gpio_remove(struct platform_device *pdev)
> +{
> +       struct p50_gpio *p50 = platform_get_drvdata(pdev);
> +
> +       platform_device_unregister(p50->keys_pdev);
> +       platform_device_unregister(p50->leds_pdev);
> +
> +       gpiod_remove_lookup_table(&p50_gpio_led_table);
> +
> +       return 0;
> +}
> +
> +static struct platform_driver p50_gpio_driver = {
> +       .driver = {
> +               .name = DRIVER_NAME,
> +       },
> +       .probe = p50_gpio_probe,
> +       .remove = p50_gpio_remove,
> +};
> +
> +/* Board setup */
> +static const struct dmi_system_id dmi_ids[] __initconst = {
> +       {
> +               .matches = {
> +                       DMI_EXACT_MATCH(DMI_PRODUCT_FAMILY, "P50")
> +               },
> +       },

But I'm a bit worried about the DMI match, it seems a bit too generic.

E.g. Lenovo also has a P50 laptop series.

For v2 please make the DMI match also on e.g. sys_vendor.

> +       {}
> +};

You should put a:

MODULE_DEVICE_TABLE(dmi, dmi_ids);

here, this will add a dmi based modalias to the module, so that it will
be automatically loaded at boot on systems which match the dmi_ids table.

> +
> +static int __init p50_module_init(void)
> +{
> +       struct resource res = DEFINE_RES_IO(P50_GPIO_IO_PORT_BASE, P50_PORT_CMD + 1);
> +
> +       if (!dmi_first_match(dmi_ids))
> +               return -ENODEV;
> +
> +       platform_driver_register(&p50_gpio_driver);
> +
> +       gpio_pdev = platform_device_register_simple(DRIVER_NAME, PLATFORM_DEVID_NONE, &res, 1);
> +       if (IS_ERR(gpio_pdev)) {
> +               pr_err("failed registering %s: %ld\n", DRIVER_NAME, PTR_ERR(gpio_pdev));
> +               platform_driver_unregister(&p50_gpio_driver);
> +               return PTR_ERR(gpio_pdev);
> +       }
> +
> +       return 0;
> +}
> +
> +static void __exit p50_module_exit(void)
> +{
> +       platform_device_unregister(gpio_pdev);
> +       platform_driver_unregister(&p50_gpio_driver);
> +}
> +
> +module_init(p50_module_init);
> +module_exit(p50_module_exit);
> +
> +MODULE_AUTHOR("Santosh Kumar Yadav, Barco NV <santoshkumar.yadav@...co.com>");
> +MODULE_DESCRIPTION("Barco P50 identify GPIOs driver");
> +MODULE_LICENSE("GPL");
> +MODULE_SOFTDEP("pre: platform:leds-gpio platform:gpio-keys-polled");

Is this softdep really necessary ? I would expect things to work fine too if
the leds-gpio and gpio-keys-polled drivers are loaded automatically after
the platform_devices for them have been created .

Regards,

Hans

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