[RFC][PATCH] Allow a set of GPIOs to be requested and configured at once - Kernel

This is a discussion on [RFC][PATCH] Allow a set of GPIOs to be requested and configured at once - Kernel ; This patch extends the gpiolib API with two new functions: - gpio_request_set() allow a set of GPIOs to be requested, and possibly configured (direction, level) at the same time, using a simple table. In case of failure, the configuration is ...

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Thread: [RFC][PATCH] Allow a set of GPIOs to be requested and configured at once

  1. [RFC][PATCH] Allow a set of GPIOs to be requested and configured at once


    This patch extends the gpiolib API with two new functions:
    - gpio_request_set() allow a set of GPIOs to be requested, and possibly
    configured (direction, level) at the same time, using a simple table.
    In case of failure, the configuration is rolled back, and the offending
    GPIO is returned to the user.
    - gpio_free_set() frees this same set of GPIOs.

    The main goal of this patch is to save gpiolib users the burden of
    requesting and configuring each GPIO, and dealing with complicated error
    handling.

    Signed-off-by: Marc Zyngier
    ---
    drivers/gpio/gpiolib.c | 54 ++++++++++++++++++++++++++++++++++++++++++++
    include/asm-generic/gpio.h | 14 +++++++++++
    2 files changed, 68 insertions(+), 0 deletions(-)

    diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
    index faa1cc6..4a8f29c 100644
    --- a/drivers/gpio/gpiolib.c
    +++ b/drivers/gpio/gpiolib.c
    @@ -813,6 +813,51 @@ done:
    }
    EXPORT_SYMBOL_GPL(gpio_request);

    +int gpio_request_set(struct gpio_config *gpio_set, int nr,
    + struct gpio_config **err)
    +{
    + int i;
    + int stat = 0;
    + int cur = 0;
    + struct gpio_config *conf = NULL;
    +
    + for (i = 0; i < nr; i++) {
    + cur = i;
    + conf = gpio_set + i;
    + stat = gpio_request(conf->gpio, conf->label);
    + if (stat)
    + goto rollback;
    +
    + switch (conf->direction) {
    + case GPIO_CONFIG_DIRECTION_INPUT:
    + stat = gpio_direction_input(conf->gpio);
    + break;
    +
    + case GPIO_CONFIG_DIRECTION_OUTPUT:
    + stat = gpio_direction_output(conf->gpio,
    + !!conf->value);
    + break;
    + }
    +
    + if (stat) {
    + gpio_free(conf->gpio);
    + goto rollback;
    + }
    + }
    +
    + return stat;
    +
    +rollback:
    + for (i = cur - 1; i >= 0; i--)
    + gpio_free(gpio_set[i].gpio);
    +
    + if (err)
    + *err = conf;
    +
    + return stat;
    +}
    +EXPORT_SYMBOL_GPL(gpio_request_set);
    +
    void gpio_free(unsigned gpio)
    {
    unsigned long flags;
    @@ -849,6 +894,15 @@ void gpio_free(unsigned gpio)
    }
    EXPORT_SYMBOL_GPL(gpio_free);

    +void gpio_free_set(struct gpio_config *gpio_set, int nr)
    +{
    + int i;
    +
    + for (i = 0; i < nr; i++)
    + gpio_free(gpio_set[i].gpio);
    +}
    +EXPORT_SYMBOL_GPL(gpio_free_set);
    +

    /**
    * gpiochip_is_requested - return string iff signal was requested
    diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
    index 81797ec..723159f 100644
    --- a/include/asm-generic/gpio.h
    +++ b/include/asm-generic/gpio.h
    @@ -111,6 +111,20 @@ extern int __must_check gpiochip_remove(struct gpio_chip *chip);
    extern int gpio_request(unsigned gpio, const char *label);
    extern void gpio_free(unsigned gpio);

    +#define GPIO_CONFIG_DIRECTION_INPUT 1
    +#define GPIO_CONFIG_DIRECTION_OUTPUT 2
    +
    +struct gpio_config {
    + unsigned gpio;
    + const char *label;
    + u16 direction;
    + u16 value;
    +};
    +
    +extern int gpio_request_set(struct gpio_config *gpio_set, int nr,
    + struct gpio_config **err);
    +extern void gpio_free_set(struct gpio_config *gpio_set, int nr);
    +
    extern int gpio_direction_input(unsigned gpio);
    extern int gpio_direction_output(unsigned gpio, int value);

    --
    1.5.4.3



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  2. Re: [RFC][PATCH] Port Arcom/Eurotech Viper over the gpio_request_set API


    As a proof of concept, use the gpio_request_set/gpio_free_set
    functions in place of the open-coded stuff used on the Viper SBC.

    Signed-off-by: Marc Zyngier
    ---
    arch/arm/mach-pxa/viper.c | 87 +++++++++++++----------------------------
    drivers/pcmcia/pxa2xx_viper.c | 49 +++++++++--------------
    2 files changed, 46 insertions(+), 90 deletions(-)

    diff --git a/arch/arm/mach-pxa/viper.c b/arch/arm/mach-pxa/viper.c
    index f5d1757..1355f91 100644
    --- a/arch/arm/mach-pxa/viper.c
    +++ b/arch/arm/mach-pxa/viper.c
    @@ -343,35 +343,21 @@ static struct pxafb_mach_info fb_info = {
    .lcd_conn = LCD_COLOR_TFT_16BPP | LCD_PCLK_EDGE_FALL,
    };

    +/* GPIO9 and 10 control FB backlight. Initialise to off */
    +static struct gpio_config viper_backlight_gpio[] = {
    + { VIPER_BCKLIGHT_EN_GPIO, "Backlight", GPIO_CONFIG_DIRECTION_OUTPUT, 0 },
    + { VIPER_LCD_EN_GPIO, "LCD", GPIO_CONFIG_DIRECTION_OUTPUT, 0 },
    +};
    +
    static int viper_backlight_init(struct device *dev)
    {
    int ret;
    + struct gpio_config *failed;

    - /* GPIO9 and 10 control FB backlight. Initialise to off */
    - ret = gpio_request(VIPER_BCKLIGHT_EN_GPIO, "Backlight");
    - if (ret)
    - goto err_request_bckl;
    -
    - ret = gpio_request(VIPER_LCD_EN_GPIO, "LCD");
    - if (ret)
    - goto err_request_lcd;
    -
    - ret = gpio_direction_output(VIPER_BCKLIGHT_EN_GPIO, 0);
    - if (ret)
    - goto err_dir;
    + ret = gpio_request_set(ARRAY_AND_SIZE(viper_backlight_gp io), &failed);

    - ret = gpio_direction_output(VIPER_LCD_EN_GPIO, 0);
    if (ret)
    - goto err_dir;
    -
    - return 0;
    -
    -err_dir:
    - gpio_free(VIPER_LCD_EN_GPIO);
    -err_request_lcd:
    - gpio_free(VIPER_BCKLIGHT_EN_GPIO);
    -err_request_bckl:
    - dev_err(dev, "Failed to setup LCD GPIOs\n");
    + dev_err(dev, "Failed to setup %s GPIO\n", failed->label);

    return ret;
    }
    @@ -386,8 +372,7 @@ static int viper_backlight_notify(int brightness)

    static void viper_backlight_exit(struct device *dev)
    {
    - gpio_free(VIPER_LCD_EN_GPIO);
    - gpio_free(VIPER_BCKLIGHT_EN_GPIO);
    + gpio_free_set(ARRAY_AND_SIZE(viper_backlight_gpio) );
    }

    static struct platform_pwm_backlight_data viper_backlight_data = {
    @@ -817,51 +802,33 @@ error_tpm:
    pr_err("viper: Couldn't %s, giving up\n", errstr);
    }

    +static struct gpio_config __initdata viper_vcore_gpios[] = {
    + { VIPER_PSU_DATA_GPIO, "PSU data", GPIO_CONFIG_DIRECTION_OUTPUT, 0, },
    + { VIPER_PSU_CLK_GPIO, "PSU clock", GPIO_CONFIG_DIRECTION_OUTPUT, 0, },
    + { VIPER_PSU_nCS_LD_GPIO, "PSU cs", GPIO_CONFIG_DIRECTION_OUTPUT, 0, },
    +};
    +
    static void __init viper_init_vcore_gpios(void)
    {
    - if (gpio_request(VIPER_PSU_DATA_GPIO, "PSU data"))
    - goto err_request_data;
    -
    - if (gpio_request(VIPER_PSU_CLK_GPIO, "PSU clock"))
    - goto err_request_clk;
    + struct gpio_config *failed;

    - if (gpio_request(VIPER_PSU_nCS_LD_GPIO, "PSU cs"))
    - goto err_request_cs;
    -
    - if (gpio_direction_output(VIPER_PSU_DATA_GPIO, 0) ||
    - gpio_direction_output(VIPER_PSU_CLK_GPIO, 0) ||
    - gpio_direction_output(VIPER_PSU_nCS_LD_GPIO, 0))
    - goto err_dir;
    + if (gpio_request_set(ARRAY_AND_SIZE(viper_vcore_gpios ), &failed)) {
    + pr_err("viper: Failed to setup %s GPIO\n", failed->label);
    + return;
    + }

    /* c/should assume redboot set the correct level ??? */
    viper_set_core_cpu_voltage(get_clk_frequency_khz(0 ), 1);
    -
    - return;
    -
    -err_dir:
    - gpio_free(VIPER_PSU_nCS_LD_GPIO);
    -err_request_cs:
    - gpio_free(VIPER_PSU_CLK_GPIO);
    -err_request_clk:
    - gpio_free(VIPER_PSU_DATA_GPIO);
    -err_request_data:
    - pr_err("viper: Failed to setup vcore control GPIOs\n");
    }

    +static struct gpio_config __initdata viper_serial_gpio[] = {
    + { VIPER_UART_SHDN_GPIO, "UARTs shutdown", GPIO_CONFIG_DIRECTION_OUTPUT, 0, },
    +};
    +
    static void __init viper_init_serial_gpio(void)
    {
    - if (gpio_request(VIPER_UART_SHDN_GPIO, "UARTs shutdown"))
    - goto err_request;
    -
    - if (gpio_direction_output(VIPER_UART_SHDN_GPIO, 0))
    - goto err_dir;
    -
    - return;
    -
    -err_dir:
    - gpio_free(VIPER_UART_SHDN_GPIO);
    -err_request:
    - pr_err("viper: Failed to setup UART shutdown GPIO\n");
    + if (gpio_request_set(ARRAY_AND_SIZE(viper_serial_gpio ), NULL))
    + pr_err("viper: Failed to setup UART shutdown GPIO\n");
    }

    #ifdef CONFIG_CPU_FREQ
    diff --git a/drivers/pcmcia/pxa2xx_viper.c b/drivers/pcmcia/pxa2xx_viper.c
    index dd10481..0f39558 100644
    --- a/drivers/pcmcia/pxa2xx_viper.c
    +++ b/drivers/pcmcia/pxa2xx_viper.c
    @@ -37,44 +37,35 @@ static struct pcmcia_irqs irqs[] = {
    { 0, gpio_to_irq(VIPER_CF_CD_GPIO), "PCMCIA_CD" }
    };

    +/* GPIO 82 is the CF power enable line. initially off */
    +static struct gpio_config viper_pcmcia_gpios[] = {
    + { VIPER_CF_CD_GPIO, "CF detect", GPIO_CONFIG_DIRECTION_INPUT, },
    + { VIPER_CF_RDY_GPIO, "CF ready", GPIO_CONFIG_DIRECTION_INPUT, },
    + { VIPER_CF_POWER_GPIO, "CF power", GPIO_CONFIG_DIRECTION_OUTPUT, 0, },
    +};
    +
    static int viper_pcmcia_hw_init(struct soc_pcmcia_socket *skt)
    {
    unsigned long flags;
    + int ret;
    + struct gpio_config *failed;

    skt->irq = gpio_to_irq(VIPER_CF_RDY_GPIO);

    - if (gpio_request(VIPER_CF_CD_GPIO, "CF detect"))
    - goto err_request_cd;
    -
    - if (gpio_request(VIPER_CF_RDY_GPIO, "CF ready"))
    - goto err_request_rdy;
    -
    - if (gpio_request(VIPER_CF_POWER_GPIO, "CF power"))
    - goto err_request_pwr;
    -
    local_irq_save(flags);

    - /* GPIO 82 is the CF power enable line. initially off */
    - if (gpio_direction_output(VIPER_CF_POWER_GPIO, 0) ||
    - gpio_direction_input(VIPER_CF_CD_GPIO) ||
    - gpio_direction_input(VIPER_CF_RDY_GPIO)) {
    - local_irq_restore(flags);
    - goto err_dir;
    - }
    -
    + ret = gpio_request_set(viper_pcmcia_gpios,
    + ARRAY_SIZE(viper_pcmcia_gpios),
    + &failed);
    +
    local_irq_restore(flags);

    - return soc_pcmcia_request_irqs(skt, irqs, ARRAY_SIZE(irqs));
    + if (ret) {
    + pr_err("viper: Failed to setup %s GPIOs\n", failed->label);
    + return ret;
    + }

    -err_dir:
    - gpio_free(VIPER_CF_POWER_GPIO);
    -err_request_pwr:
    - gpio_free(VIPER_CF_RDY_GPIO);
    -err_request_rdy:
    - gpio_free(VIPER_CF_CD_GPIO);
    -err_request_cd:
    - printk(KERN_ERR "viper: Failed to setup PCMCIA GPIOs\n");
    - return -1;
    + return soc_pcmcia_request_irqs(skt, irqs, ARRAY_SIZE(irqs));
    }

    /*
    @@ -83,9 +74,7 @@ err_request_cd:
    static void viper_pcmcia_hw_shutdown(struct soc_pcmcia_socket *skt)
    {
    soc_pcmcia_free_irqs(skt, irqs, ARRAY_SIZE(irqs));
    - gpio_free(VIPER_CF_POWER_GPIO);
    - gpio_free(VIPER_CF_RDY_GPIO);
    - gpio_free(VIPER_CF_CD_GPIO);
    + gpio_free_set(viper_pcmcia_gpios, ARRAY_SIZE(viper_pcmcia_gpios));
    }

    static void viper_pcmcia_socket_state(struct soc_pcmcia_socket *skt,
    --
    1.5.4.3


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