[PATCH v3 8/8] reset: Add driver for gpio-controlled reset pins
Philipp Zabel
p.zabel at pengutronix.de
Tue Feb 19 22:35:32 EST 2013
This driver implements a reset controller device that toggles gpios
connected to reset pins of peripheral ICs. The delay between assertion
and de-assertion of the reset signal can be configured.
Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
---
Changes since v2:
- Fill reset_controller_dev.owner field.
- Renamed "gpios" device tree property to "reset-gpios".
- Added device tree binding documentation.
---
.../devicetree/bindings/reset/gpio-reset.txt | 32 ++++
drivers/reset/Kconfig | 13 ++
drivers/reset/Makefile | 1 +
drivers/reset/gpio-reset.c | 189 ++++++++++++++++++++
4 files changed, 235 insertions(+)
create mode 100644 Documentation/devicetree/bindings/reset/gpio-reset.txt
create mode 100644 drivers/reset/gpio-reset.c
diff --git a/Documentation/devicetree/bindings/reset/gpio-reset.txt b/Documentation/devicetree/bindings/reset/gpio-reset.txt
new file mode 100644
index 0000000..9dd8781
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/gpio-reset.txt
@@ -0,0 +1,31 @@
+GPIO reset controller
+=====================
+
+A GPIO reset controller controls a number of GPIOs that are connected
+to reset pins of peripheral ICs.
+
+Please also refer to reset.txt in this directory for common reset
+controller binding usage.
+
+Required properties:
+- compatible: Should be "gpio-reset"
+- reset-gpios: List of gpios used as reset lines. The gpio specifier for this
+ property depends on the gpio controller that provides the gpio.
+- reset-delays: List of delays in ms. The corresponding gpio reset line is
+ asserted for this duration to reset.
+- #reset-cells: 1, see below
+
+example:
+
+gpio_reset: gpio-reset {
+ compatible = "gpio-reset";
+ reset-gpios = <&gpio5 0 1>; /* active-low */
+ reset-delays = <10>; /* 10 ms */
+ #reset-cells = <1>;
+};
+
+/* Device with nRESET pin connected to GPIO5_0 */
+sii902x at 39 {
+ /* ... */
+ resets = <&gpio_reset 0>; /* active-low GPIO5_0, 10 ms reset delay */
+};
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index c9d04f7..e728d36 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -11,3 +11,16 @@ 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..80a1807
--- /dev/null
+++ b/drivers/reset/gpio-reset.c
@@ -0,0 +1,189 @@
+/*
+ * 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, "reset-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,
+ "reset-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.owner = THIS_MODULE;
+ 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
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