[U-Boot] [PATCH v3 51/54] dm: Add a system reset uclass
Simon Glass
sjg at chromium.org
Tue Jun 23 23:39:13 CEST 2015
It is common for system reset to be available at multiple levels in modern
hardware. For example, an SoC may provide a reset option, and a board may
provide its own reset for reasons of security or thoroughness. It is useful
to be able to model this hardware without hard-coding the behaviour in the
SoC or board. Also there is a distinction sometimes between resetting just
the CPU (leaving GPIO state alone) and resetting all the PMICs, just cutting
power.
To achieve this, add a simple system reset uclass. It allows multiple devices
to provide reset functionality and provides a way to walk through them,
requesting a particular reset type until is it provided.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
Changes in v3: None
Changes in v2: None
drivers/misc/Kconfig | 9 +++++++
drivers/misc/Makefile | 1 +
drivers/misc/reset-uclass.c | 62 +++++++++++++++++++++++++++++++++++++++++++++
include/dm/uclass-id.h | 1 +
include/reset.h | 62 +++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 135 insertions(+)
create mode 100644 drivers/misc/reset-uclass.c
create mode 100644 include/reset.h
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 64b07a3..3b7f76a 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -73,3 +73,12 @@ config PCA9551_I2C_ADDR
default 0x60
help
The I2C address of the PCA9551 LED controller.
+
+config RESET
+ bool "Enable support for reset drivers"
+ depends on DM
+ help
+ Enable reset drivers which can be used to reset the CPU or board.
+ Each driver can provide a reset method which will be called to
+ effect a reset. The uclass will try all available drivers when
+ reset_walk() is called.
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 120babc..5da5178 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -32,3 +32,4 @@ obj-$(CONFIG_TWL4030_LED) += twl4030_led.o
obj-$(CONFIG_FSL_IFC) += fsl_ifc.o
obj-$(CONFIG_FSL_SEC_MON) += fsl_sec_mon.o
obj-$(CONFIG_PCA9551_LED) += pca9551_led.o
+obj-$(CONFIG_RESET) += reset-uclass.o
diff --git a/drivers/misc/reset-uclass.c b/drivers/misc/reset-uclass.c
new file mode 100644
index 0000000..ba27757
--- /dev/null
+++ b/drivers/misc/reset-uclass.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ * Written by Simon Glass <sjg at chromium.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <reset.h>
+#include <dm.h>
+#include <errno.h>
+#include <regmap.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/root.h>
+#include <linux/err.h>
+
+int reset_request(struct udevice *dev, enum reset_t type)
+{
+ struct reset_ops *ops = reset_get_ops(dev);
+
+ if (!ops->request)
+ return -ENOSYS;
+
+ return ops->request(dev, type);
+}
+
+void reset_walk(enum reset_t type)
+{
+ struct udevice *dev;
+ int ret = 0;
+
+ while (ret != -EINPROGRESS && type < RESET_COUNT) {
+ for (uclass_first_device(UCLASS_RESET, &dev);
+ dev;
+ uclass_next_device(&dev)) {
+ ret = reset_request(dev, type);
+ if (ret == -EINPROGRESS)
+ break;
+ }
+ }
+
+ /* Wait for the reset to take effect */
+ mdelay(100);
+
+ /* Still no reset? Give up */
+ printf("Reset not supported on this platform\n");
+ hang();
+}
+
+/**
+ * reset_cpu() - calls reset_walk(RESET_WARM)
+ */
+void reset_cpu(ulong addr)
+{
+ reset_walk(RESET_WARM);
+}
+
+UCLASS_DRIVER(reset) = {
+ .id = UCLASS_RESET,
+ .name = "reset",
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index 5bb602f..fc486f2 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -45,6 +45,7 @@ enum uclass_id {
UCLASS_PINCTRL, /* Pin multiplexing control */
UCLASS_PMIC, /* PMIC I/O device */
UCLASS_REGULATOR, /* Regulator device */
+ UCLASS_RESET, /* Reset device */
UCLASS_RTC, /* Real time clock device */
UCLASS_SERIAL, /* Serial UART */
UCLASS_SPI, /* SPI bus */
diff --git a/include/reset.h b/include/reset.h
new file mode 100644
index 0000000..d29e108
--- /dev/null
+++ b/include/reset.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg at chromium.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef __RESET_H
+#define __RESET_H
+
+enum reset_t {
+ RESET_WARM, /* Reset CPU, keep GPIOs active */
+ RESET_COLD, /* Reset CPU and GPIOs */
+ RESET_POWER, /* Reset PMIC (remove and restore power) */
+
+ RESET_COUNT,
+};
+
+struct reset_ops {
+ /**
+ * request() - request a reset of the given type
+ *
+ * Note that this function may return before the reset takes effect.
+ *
+ * @type: Reset type to request
+ * @return -EINPROGRESS if the reset has been started and
+ * will complete soon, -EPROTONOSUPPORT if not supported
+ * by this device, 0 if the reset has already happened
+ * (in which case this method will not actually return)
+ */
+ int (*request)(struct udevice *dev, enum reset_t type);
+};
+
+#define reset_get_ops(dev) ((struct reset_ops *)(dev)->driver->ops)
+
+/**
+ * reset_request() - request a reset
+ *
+ * @type: Reset type to request
+ * @return 0 if OK, -EPROTONOSUPPORT if not supported by this device
+ */
+int reset_request(struct udevice *dev, enum reset_t type);
+
+/**
+ * reset_walk() - cause a reset
+ *
+ * This works through the available reset devices until it finds one that can
+ * perform a reset. If the provided reset type is not available, the next one
+ * will be tried.
+ *
+ * If this function fails to reset, it will display a message and halt
+ *
+ * @type: Reset type to request
+ */
+void reset_walk(enum reset_t type);
+
+/**
+ * reset_cpu() - calls reset_walk(RESET_WARM)
+ */
+void reset_cpu(ulong addr);
+
+#endif
--
2.4.3.573.g4eafbef
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