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 ---
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@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@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