From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Brandt Subject: [PATCH 1/3] power: reset: Add Renesas reset driver Date: Mon, 13 Feb 2017 13:25:30 -0500 Message-ID: <20170213182532.4042-2-chris.brandt@renesas.com> References: <20170213182532.4042-1-chris.brandt@renesas.com> Return-path: In-Reply-To: <20170213182532.4042-1-chris.brandt@renesas.com> Sender: linux-pm-owner@vger.kernel.org To: Sebastian Reichel , Rob Herring , Mark Rutland , Simon Horman Cc: linux-renesas-soc@vger.kernel.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, Chris Brandt List-Id: devicetree@vger.kernel.org Some Renesas SoCs do not have a reset register and the only way to do a SW controlled reset is to use the watchdog timer. Additionally, since all the WDT timeout options are so quick, a system reset is about the only thing it's good for. Signed-off-by: Chris Brandt --- drivers/power/reset/Kconfig | 9 ++++ drivers/power/reset/Makefile | 1 + drivers/power/reset/renesas-reset.c | 103 ++++++++++++++++++++++++++++++++++++ 3 files changed, 113 insertions(+) create mode 100644 drivers/power/reset/renesas-reset.c diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig index b8caccc..e3100c9 100644 --- a/drivers/power/reset/Kconfig +++ b/drivers/power/reset/Kconfig @@ -130,6 +130,15 @@ config POWER_RESET_QNAP Say Y if you have a QNAP NAS. +config POWER_RESET_RENESAS + tristate "Renesas WDT reset driver" + depends on ARCH_RENESAS || COMPILE_TEST + depends on HAS_IOMEM + help + Reboot support for Renesas SoCs with WDT reset. + Some Renesas SoCs do not have a reset register and the only way + to do a SW controlled reset is to use the watchdog timer. + config POWER_RESET_RESTART bool "Restart power-off driver" help diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile index 11dae3b..a78a56c 100644 --- a/drivers/power/reset/Makefile +++ b/drivers/power/reset/Makefile @@ -13,6 +13,7 @@ obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o +obj-$(CONFIG_POWER_RESET_RENESAS) += renesas-reset.o obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o diff --git a/drivers/power/reset/renesas-reset.c b/drivers/power/reset/renesas-reset.c new file mode 100644 index 0000000..dede029 --- /dev/null +++ b/drivers/power/reset/renesas-reset.c @@ -0,0 +1,103 @@ +/* + * Renesas WDT Reset Driver + * + * Copyright (C) 2017 Renesas Electronics America, Inc. + * Copyright (C) 2017 Chris Brandt + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * based on rmobile-reset.c + * + */ + +#include +#include +#include +#include +#include +#include +#include + +/* Watchdog Timer Registers */ +#define WTCSR 0 +#define WTCNT 2 +#define WRCSR 4 + +static void __iomem *base; + +static int wdt_reset_handler(struct notifier_block *this, + unsigned long mode, void *cmd) +{ + pr_debug("%s %lu\n", __func__, mode); + + /* Dummy read (must read WRCSR:WOVF at least once before clearing) */ + readw(base + WRCSR); + + writew(0xA500, base + WRCSR); /* Clear WOVF */ + writew(0x5A5F, base + WRCSR); /* Reset Enable */ + writew(0x5A00, base + WTCNT); /* Counter to 00 */ + writew(0xA578, base + WTCSR); /* Start timer */ + + /* Wait for WDT overflow */ + while (1) + ; + + return NOTIFY_DONE; +} + +static struct notifier_block wdt_reset_nb = { + .notifier_call = wdt_reset_handler, + .priority = 192, +}; + +static int wdt_reset_probe(struct platform_device *pdev) +{ + int error; + + base = of_iomap(pdev->dev.of_node, 0); + if (!base) + return -ENODEV; + + error = register_restart_handler(&wdt_reset_nb); + if (error) { + dev_err(&pdev->dev, + "cannot register restart handler (err=%d)\n", error); + goto fail_unmap; + } + + return 0; + +fail_unmap: + iounmap(base); + return error; +} + +static int wdt_reset_remove(struct platform_device *pdev) +{ + unregister_restart_handler(&wdt_reset_nb); + iounmap(base); + return 0; +} + +static const struct of_device_id wdt_reset_of_match[] = { + { .compatible = "renesas,wdt-reset", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, wdt_reset_of_match); + +static struct platform_driver wdt_reset_driver = { + .probe = wdt_reset_probe, + .remove = wdt_reset_remove, + .driver = { + .name = "wdt_reset", + .of_match_table = wdt_reset_of_match, + }, +}; + +module_platform_driver(wdt_reset_driver); + +MODULE_DESCRIPTION("Renesas WDT Reset Driver"); +MODULE_AUTHOR("Chris Brandt "); +MODULE_LICENSE("GPL v2"); -- 2.10.1