| Message ID | 1360776872-18584-9-git-send-email-p.zabel@pengutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Feb 13, 2013 at 06:34:32PM +0100, Philipp Zabel wrote:
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Just be aware that PXA has a "gpio reset" facility which is used for SoC
reset - see arch/arm/mach-pxa/reset.c
The use of gpio-reset would be ambiguous... or maybe PXA's usage could be
combined somehow with this?
Hi Russell, Am Donnerstag, den 14.02.2013, 10:56 +0000 schrieb Russell King - ARM Linux: > On Wed, Feb 13, 2013 at 06:34:32PM +0100, Philipp Zabel wrote: > > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> > > Just be aware that PXA has a "gpio reset" facility which is used for SoC > reset - see arch/arm/mach-pxa/reset.c > > The use of gpio-reset would be ambiguous... or maybe PXA's usage could be > combined somehow with this? thank you for pointing this out. The PXA gpio reset code is used for system/board reset and fiddles with the reset line to trigger all possible types of reset without needing configuration. The code I suggest is targeted at resetting peripheral devices, like I2C and SPI ICs with a reset line connected via GPIO, and it has to be configured for either active-high or active-low GPIOs. Should this be combined? I wonder if it would be worth the effort to make the PXA gpio reset go through this reset API, as there isn't even a struct device that would be the reset "consumer". In fact, I don't even think most drivers that currently implement gpio resets themselves would gain much from switching to another level of abstraction, unless the SoC already has an on-chip reset controller anyway - in which case this would mostly increase overall consistency. regards Philipp
On Wed, Feb 13, 2013 at 06:34:32PM +0100, Philipp Zabel wrote: > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> You must have something to mention in the commit log when you add such a new reset controller. > --- > drivers/reset/Kconfig | 13 +++ > drivers/reset/Makefile | 1 + > drivers/reset/gpio-reset.c | 188 ++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 202 insertions(+) > create mode 100644 drivers/reset/gpio-reset.c ... > +static int gpio_reset_probe(struct platform_device *pdev) > +{ > + struct device_node *np = pdev->dev.of_node; > + struct gpio_reset_data *drvdata; > + enum of_gpio_flags flags; > + u32 *delays = NULL; > + int ret; > + int i; > + > + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL); > + if (drvdata == NULL) > + return -ENOMEM; > + > + drvdata->nr_gpios = of_gpio_named_count(np, "gpios"); I would suggest to name the property reset-gpios. All the properties and compatible used in the driver should be documented in the binding doc. Shawn > + if (drvdata->nr_gpios < 1) > + return -EINVAL; > + > + drvdata->gpios = devm_kzalloc(&pdev->dev, sizeof(struct gpio_reset) * > + drvdata->nr_gpios, GFP_KERNEL); > + if (drvdata->gpios == NULL) > + return -ENOMEM; > + > + if (of_find_property(np, "reset-delays", NULL)) { > + delays = devm_kzalloc(&pdev->dev, sizeof(u32) * > + drvdata->nr_gpios, GFP_KERNEL); > + if (delays == NULL) > + return -ENOMEM; > + > + ret = of_property_read_u32_array(np, "reset-delays", delays, > + drvdata->nr_gpios); > + if (ret < 0) > + return ret; > + } > + > + for (i = 0; i < drvdata->nr_gpios; i++) { > + drvdata->gpios[i].gpio = of_get_named_gpio_flags(np, "gpios", > + i, &flags); > + if (drvdata->gpios[i].gpio < 0) { > + dev_err(&pdev->dev, "invalid gpio for reset %d\n", i); > + return drvdata->gpios[i].gpio; > + } > + > + /* > + * The flags are also used to remember whether a given GPIO > + * reset is active-low. > + */ > + if (flags & OF_GPIO_ACTIVE_LOW) > + drvdata->gpios[i].flags = GPIOF_OUT_INIT_HIGH; > + else > + drvdata->gpios[i].flags = GPIOF_OUT_INIT_LOW; > + > + ret = devm_gpio_request_one(&pdev->dev, drvdata->gpios[i].gpio, > + drvdata->gpios[i].flags, NULL); > + if (ret < 0) { > + dev_err(&pdev->dev, "failed to request gpio %d for reset %d\n", > + drvdata->gpios[i].gpio, i); > + return ret; > + } > + > + if (delays != NULL) > + drvdata->gpios[i].delay_ms = delays[i]; > + else > + drvdata->gpios[i].delay_ms = -1; /* .reset returns -ENOSYS */ > + } > + > + devm_kfree(&pdev->dev, delays); > + > + drvdata->rcdev.of_node = np; > + drvdata->rcdev.ops = &gpio_reset_ops; > + reset_controller_register(&drvdata->rcdev); > + > + platform_set_drvdata(pdev, drvdata); > + > + return 0; > +} > + > +static int gpio_reset_remove(struct platform_device *pdev) > +{ > + struct gpio_reset_data *drvdata = platform_get_drvdata(pdev); > + > + reset_controller_unregister(&drvdata->rcdev); > + > + return 0; > +} > + > +static struct of_device_id gpio_reset_dt_ids[] = { > + { .compatible = "gpio-reset" }, > + { } > +}; > + > +static struct platform_driver gpio_reset_driver = { > + .probe = gpio_reset_probe, > + .remove = gpio_reset_remove, > + .driver = { > + .name = "gpio-reset", > + .owner = THIS_MODULE, > + .of_match_table = of_match_ptr(gpio_reset_dt_ids), > + }, > +}; > + > +module_platform_driver(gpio_reset_driver); > -- > 1.7.10.4 >
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index 66ac385..bdf799a 100644 --- a/drivers/reset/Kconfig +++ b/drivers/reset/Kconfig @@ -7,3 +7,16 @@ menuconfig RESET_CONTROLLER via GPIOs or SoC-internal reset controller modules. If unsure, say no. + +if RESET_CONTROLLER + +config RESET_GPIO + tristate "GPIO reset controller support" + depends on GENERIC_GPIO + help + This driver provides support for reset lines that are controlled + directly by GPIOs. + The delay between assertion and de-assertion of the reset signal + can be configured. + +endif diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index 1e2d83f..b854f20 100644 --- a/drivers/reset/Makefile +++ b/drivers/reset/Makefile @@ -1 +1,2 @@ obj-$(CONFIG_RESET_CONTROLLER) += core.o +obj-$(CONFIG_RESET_GPIO) += gpio-reset.o diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c new file mode 100644 index 0000000..c7ca858 --- /dev/null +++ b/drivers/reset/gpio-reset.c @@ -0,0 +1,188 @@ +/* + * Copyright 2013 Philipp Zabel, Pengutronix + */ +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/gpio.h> +#include <linux/module.h> +#include <linux/of_gpio.h> +#include <linux/platform_device.h> +#include <linux/reset-controller.h> + +struct gpio_reset { + unsigned int gpio; + unsigned long flags; + unsigned int delay_ms; +}; + +struct gpio_reset_data { + struct reset_controller_dev rcdev; + struct gpio_reset *gpios; + int nr_gpios; +}; + +static void __gpio_reset_set(struct gpio_reset_data *drvdata, + unsigned long gpio_idx, int asserted) +{ + int value = asserted; + + if (drvdata->gpios[gpio_idx].flags == GPIOF_OUT_INIT_HIGH) + value = !value; + + gpio_set_value(drvdata->gpios[gpio_idx].gpio, value); +} + +static int gpio_reset(struct reset_controller_dev *rcdev, + unsigned long gpio_idx) +{ + struct gpio_reset_data *drvdata = container_of(rcdev, + struct gpio_reset_data, rcdev); + + if (gpio_idx >= drvdata->nr_gpios) + return -EINVAL; + + if (drvdata->gpios[gpio_idx].delay_ms < 0) + return -ENOSYS; + + __gpio_reset_set(drvdata, gpio_idx, 1); + mdelay(drvdata->gpios[gpio_idx].delay_ms); + __gpio_reset_set(drvdata, gpio_idx, 0); + + return 0; +} + +static int gpio_reset_assert(struct reset_controller_dev *rcdev, + unsigned long gpio_idx) +{ + struct gpio_reset_data *drvdata = container_of(rcdev, + struct gpio_reset_data, rcdev); + + if (gpio_idx >= drvdata->nr_gpios) + return -EINVAL; + + __gpio_reset_set(drvdata, gpio_idx, 1); + + return 0; +} + +static int gpio_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long gpio_idx) +{ + struct gpio_reset_data *drvdata = container_of(rcdev, + struct gpio_reset_data, rcdev); + + if (gpio_idx >= drvdata->nr_gpios) + return -EINVAL; + + __gpio_reset_set(drvdata, gpio_idx, 0); + + return 0; +} + +static struct reset_control_ops gpio_reset_ops = { + .reset = gpio_reset, + .assert = gpio_reset_assert, + .deassert = gpio_reset_deassert, +}; + +static int gpio_reset_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct gpio_reset_data *drvdata; + enum of_gpio_flags flags; + u32 *delays = NULL; + int ret; + int i; + + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL); + if (drvdata == NULL) + return -ENOMEM; + + drvdata->nr_gpios = of_gpio_named_count(np, "gpios"); + if (drvdata->nr_gpios < 1) + return -EINVAL; + + drvdata->gpios = devm_kzalloc(&pdev->dev, sizeof(struct gpio_reset) * + drvdata->nr_gpios, GFP_KERNEL); + if (drvdata->gpios == NULL) + return -ENOMEM; + + if (of_find_property(np, "reset-delays", NULL)) { + delays = devm_kzalloc(&pdev->dev, sizeof(u32) * + drvdata->nr_gpios, GFP_KERNEL); + if (delays == NULL) + return -ENOMEM; + + ret = of_property_read_u32_array(np, "reset-delays", delays, + drvdata->nr_gpios); + if (ret < 0) + return ret; + } + + for (i = 0; i < drvdata->nr_gpios; i++) { + drvdata->gpios[i].gpio = of_get_named_gpio_flags(np, "gpios", + i, &flags); + if (drvdata->gpios[i].gpio < 0) { + dev_err(&pdev->dev, "invalid gpio for reset %d\n", i); + return drvdata->gpios[i].gpio; + } + + /* + * The flags are also used to remember whether a given GPIO + * reset is active-low. + */ + if (flags & OF_GPIO_ACTIVE_LOW) + drvdata->gpios[i].flags = GPIOF_OUT_INIT_HIGH; + else + drvdata->gpios[i].flags = GPIOF_OUT_INIT_LOW; + + ret = devm_gpio_request_one(&pdev->dev, drvdata->gpios[i].gpio, + drvdata->gpios[i].flags, NULL); + if (ret < 0) { + dev_err(&pdev->dev, "failed to request gpio %d for reset %d\n", + drvdata->gpios[i].gpio, i); + return ret; + } + + if (delays != NULL) + drvdata->gpios[i].delay_ms = delays[i]; + else + drvdata->gpios[i].delay_ms = -1; /* .reset returns -ENOSYS */ + } + + devm_kfree(&pdev->dev, delays); + + drvdata->rcdev.of_node = np; + drvdata->rcdev.ops = &gpio_reset_ops; + reset_controller_register(&drvdata->rcdev); + + platform_set_drvdata(pdev, drvdata); + + return 0; +} + +static int gpio_reset_remove(struct platform_device *pdev) +{ + struct gpio_reset_data *drvdata = platform_get_drvdata(pdev); + + reset_controller_unregister(&drvdata->rcdev); + + return 0; +} + +static struct of_device_id gpio_reset_dt_ids[] = { + { .compatible = "gpio-reset" }, + { } +}; + +static struct platform_driver gpio_reset_driver = { + .probe = gpio_reset_probe, + .remove = gpio_reset_remove, + .driver = { + .name = "gpio-reset", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(gpio_reset_dt_ids), + }, +}; + +module_platform_driver(gpio_reset_driver);
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> --- drivers/reset/Kconfig | 13 +++ drivers/reset/Makefile | 1 + drivers/reset/gpio-reset.c | 188 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 202 insertions(+) create mode 100644 drivers/reset/gpio-reset.c