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 v2:
- fix assert_prop initial value
---
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..77d4bd7
--- /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-boot-asserted";
+ const char *gpio_con_id = "reset";
+ struct reset_controller_dev *rcdev;
+ struct reset_control *rstc;
+ struct gpio_desc *gpiod;
+ char scratch[48];
+ bool asserted;
+ 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;
+
+ ret = -ENOMEM;
+ rcdev = reset_get_gpio_rcdev();
+ if (!rcdev)
+ goto err_put;
+
+ rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
+ if (!rstc)
+ goto err_put;
+
+ rstc->dev = dev;
+ rstc->rcdev = rcdev;
+ rstc->id = desc_to_gpio(gpiod);
+
+ return rstc;
+
+err_put:
+ gpiod_put(gpiod);
+ return ERR_PTR(ret);
+}
+
+bool reset_control_is_gpio(struct reset_control *rstc)
+{
+ return rstc->rcdev == gpio_rcdev;
+}
+
+void gpio_reset_control_put(struct reset_control *rstc)
+{
+ struct gpio_desc *gpiod = gpio_to_desc(rstc->id);
+
+ if (gpiod)
+ gpiod_put(gpiod);
+}
diff --git a/drivers/reset/reset-core.h b/drivers/reset/reset-core.h
new file mode 100644
index 0000000..55bd297
--- /dev/null
+++ b/drivers/reset/reset-core.h
@@ -0,0 +1,47 @@
+/*
+ * Reset Controller framework
+ *
+ * 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.
+ */
+
+#ifndef __RESET_CORE_H__
+#define __RESET_CORE_H__
+
+/**
+ * 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;
+};
+
+#if IS_ENABLED(CONFIG_RESET_GPIO)
+struct reset_control *gpio_reset_control_get(struct device *dev, const char *id);
+bool reset_control_is_gpio(struct reset_control *rstc);
+void gpio_reset_control_put(struct reset_control *rstc);
+#else
+static inline struct reset_control *gpio_reset_control_get(struct device *dev,
+ const char *id)
+{
+ return -ENOSYS;
+}
+
+static inline bool reset_control_is_gpio(struct reset_control *rstc)
+{
+ return false;
+}
+
+static inline void gpio_reset_control_put(struct reset_control *rstc) { }
+#endif
+
+#endif
--
1.8.5.2
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