dm: Add a system reset uclass

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@chromium.org>

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 13b512158aadeca705bce9eba6078c92c4282486..ebcd58c46dd09c5ee5724d7c6754b482bf618c49 100644 (file)
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -81,3 +81,12 @@ 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 120babc4b5d87e2ac344f96d1f4849f6de80ce54..5da5178737179f07420100bf2c0c51c52dd861bf 100644 (file)
--- 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 (file)
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@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 93a38575bdf246d76fd9a778363e8e9f1ea3e11d..b993fc0a0639c87868c4c8e879d92a23d22e1eab 100644 (file)
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -44,6 +44,7 @@ enum uclass_id {
        UCLASS_PCI_GENERIC,     /* Generic PCI bus device */
        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 (file)
index 0000000..d29e108
--- /dev/null
+++ b/include/reset.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@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