Hi Philipp,
On Mon, Jan 06, 2014 at 06:55:03PM +0100, Philipp Zabel wrote:
> This adds support for GPIO controlled reset pins on peripheral ICs to the reset
> controller framework. Currently there is no support for specifying a delay
> between assertion and de-assertion of the reset signal, so this has to be
> handled by the drivers.
>
> Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> ---
> Changes since v1:
> - Since (<name>-)reset-gpios is already a common pattern, I have dropped the
> additional reset-gpio-names property.
> - A boolean (<name>-)reset-boot-asserted is added to keep GPIOs asserted when
> requesting them.
> - Rebased onto Maxime Ripard's of_reset_control_get patch
> ---
> drivers/reset/Kconfig | 17 ++++++
> drivers/reset/Makefile | 9 ++-
> drivers/reset/core.c | 29 +++++-----
> drivers/reset/gpio-reset.c | 137 +++++++++++++++++++++++++++++++++++++++++++++
> drivers/reset/reset-core.h | 47 ++++++++++++++++
> 5 files changed, 224 insertions(+), 15 deletions(-)
> create mode 100644 drivers/reset/gpio-reset.c
> create mode 100644 drivers/reset/reset-core.h
>
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index c9d04f7..a6b12a9 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -10,4 +10,21 @@ menuconfig RESET_CONTROLLER
> This framework is designed to abstract reset handling of devices
> via GPIOs or SoC-internal reset controller modules.
>
> + If the device tree contains any resets or reset-gpio properties,
> + this probably should be enabled.
> +
> If unsure, say no.
> +
> +if RESET_CONTROLLER
> +
> +menuconfig RESET_GPIO
> + bool "GPIO Reset Support"
> + depends on GPIOLIB
> + default y if GPIOLIB
> + help
> + GPIO Reset Controller support.
> +
> + This option lets the reset controller framework handle reset lines
> + connected to GPIOs.
> +
> +endif
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index cc29832..764bb74 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -1,2 +1,9 @@
> -obj-$(CONFIG_RESET_CONTROLLER) += core.o
> +reset-core-objs := core.o
> +
> +obj-$(CONFIG_RESET_CONTROLLER) += reset-core.o
> +
> +ifeq ($(CONFIG_RESET_GPIO),y)
> + reset-core-objs += gpio-reset.o
> +endif
> +
> obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
> index baeaf82..6bfd2d2 100644
> --- a/drivers/reset/core.c
> +++ b/drivers/reset/core.c
> @@ -18,23 +18,12 @@
> #include <linux/reset-controller.h>
> #include <linux/slab.h>
>
> +#include "reset-core.h"
> +
> static DEFINE_MUTEX(reset_controller_list_mutex);
> static LIST_HEAD(reset_controller_list);
>
> /**
> - * struct reset_control - a reset control
> - * @rcdev: a pointer to the reset controller device
> - * this reset control belongs to
> - * @id: ID of the reset controller in the reset
> - * controller device
> - */
> -struct reset_control {
> - struct reset_controller_dev *rcdev;
> - struct device *dev;
> - unsigned int id;
> -};
> -
> -/**
> * of_reset_simple_xlate - translate reset_spec to the reset line number
> * @rcdev: a pointer to the reset controller device
> * @reset_spec: reset line specifier as found in the device tree
> @@ -149,6 +138,8 @@ struct reset_control *of_reset_control_get(struct device_node *node,
> "reset-names", id);
> ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
> index, &args);
> + if (index == -EINVAL)
> + return ERR_PTR(-ENOENT);
> if (ret)
> return ERR_PTR(ret);
>
> @@ -209,6 +200,13 @@ struct reset_control *reset_control_get(struct device *dev, const char *id)
> if (!IS_ERR(rstc))
> rstc->dev = dev;
>
> + /*
> + * If there is no dedicated reset controller device, check if we have
> + * a reset line controlled by a GPIO instead.
> + */
> + if (PTR_ERR(rstc) == -ENOENT)
> + return gpio_reset_control_get(dev, id);
> +
> return rstc;
> }
> EXPORT_SYMBOL_GPL(reset_control_get);
> @@ -223,7 +221,10 @@ void reset_control_put(struct reset_control *rstc)
> if (IS_ERR(rstc))
> return;
>
> - module_put(rstc->rcdev->owner);
> + if (reset_control_is_gpio(rstc))
> + gpio_reset_control_put(rstc);
> + else
> + module_put(rstc->rcdev->owner);
> kfree(rstc);
> }
> EXPORT_SYMBOL_GPL(reset_control_put);
> diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c
> new file mode 100644
> index 0000000..78cd023
> --- /dev/null
> +++ b/drivers/reset/gpio-reset.c
> @@ -0,0 +1,137 @@
> +/*
> + * GPIO Reset Controller
> + *
> + * Copyright 2013 Philipp Zabel, Pengutronix
> + *
> + * 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, or
> + * (at your option) any later version.
> + */
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/reset-controller.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +#include "reset-core.h"
> +
> +/*
> + * Global GPIO reset controller
> + */
> +static struct reset_controller_dev *gpio_rcdev;
> +
> +static int gpio_reset_set(struct reset_controller_dev *rcdev,
> + unsigned int gpio, int asserted)
> +{
> + struct gpio_desc *gpiod = gpio_to_desc(gpio);
> +
> + if (!gpiod)
> + return -EINVAL;
> +
> + gpiod_set_value_cansleep(gpiod, asserted);
> +
> + return 0;
> +}
> +
> +static int gpio_reset_assert(struct reset_controller_dev *rcdev,
> + unsigned long id)
> +{
> + return gpio_reset_set(rcdev, id, 1);
> +}
> +
> +static int gpio_reset_deassert(struct reset_controller_dev *rcdev,
> + unsigned long id)
> +{
> + return gpio_reset_set(rcdev, id, 0);
> +}
> +
> +static struct reset_control_ops gpio_reset_ops = {
> + .assert = gpio_reset_assert,
> + .deassert = gpio_reset_deassert,
> +};
> +
> +struct reset_controller_dev *reset_get_gpio_rcdev(void)
> +{
> + if (gpio_rcdev)
> + return gpio_rcdev;
> +
> + gpio_rcdev = kzalloc(sizeof(*gpio_rcdev), GFP_KERNEL);
> + if (!gpio_rcdev)
> + return NULL;
> +
> + gpio_rcdev->owner = THIS_MODULE;
> + gpio_rcdev->ops = &gpio_reset_ops;
> +
> + reset_controller_register(gpio_rcdev);
> +
> + return gpio_rcdev;
> +}
> +
> +struct reset_control *gpio_reset_control_get(struct device *dev, const char *id)
> +{
> + const char *assert_prop = "reset-initially-asserted";
I guess you meant reset-boot-asserted here, right?
> + const char *gpio_con_id = "reset";
> + struct reset_controller_dev *rcdev;
> + struct reset_control *rstc;
> + struct gpio_desc *gpiod;
> + bool asserted = false;
> + char scratch[48];
> + int ret;
> +
> + if (id) {
> + snprintf(scratch, 48, "%s-reset-boot-asserted", id);
> + assert_prop = scratch;
> + }
> +
> + asserted = of_property_read_bool(dev->of_node, assert_prop);
> +
> + if (id) {
> + snprintf(scratch, 48, "%s-reset", id);
> + gpio_con_id = scratch;
> + }
> +
> + gpiod = gpiod_get(dev, gpio_con_id);
> + if (IS_ERR(gpiod)) {
> + dev_err(dev, "Failed to get GPIO reset: %ld\n", PTR_ERR(gpiod));
> + return ERR_CAST(gpiod);
> + }
> +
> + ret = gpiod_direction_output(gpiod, asserted);
> + if (ret < 0)
> + goto err_put;
What happens if the GPIO is active low? I see no way in your binding
and driver to give that information, and that would change the
behaviour quite a bit.
Thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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