diff options
Diffstat (limited to 'drivers/watchdog/pic32-wdt.c')
| -rw-r--r-- | drivers/watchdog/pic32-wdt.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/drivers/watchdog/pic32-wdt.c b/drivers/watchdog/pic32-wdt.c new file mode 100644 index 000000000..41715d68d --- /dev/null +++ b/drivers/watchdog/pic32-wdt.c @@ -0,0 +1,244 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * PIC32 watchdog driver + * + * Joshua Henderson <joshua.henderson@microchip.com> + * Copyright (c) 2016, Microchip Technology Inc. + */ +#include <linux/clk.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/pm.h> +#include <linux/watchdog.h> + +#include <asm/mach-pic32/pic32.h> + +/* Watchdog Timer Registers */ +#define WDTCON_REG 0x00 + +/* Watchdog Timer Control Register fields */ +#define WDTCON_WIN_EN BIT(0) +#define WDTCON_RMCS_MASK 0x0003 +#define WDTCON_RMCS_SHIFT 0x0006 +#define WDTCON_RMPS_MASK 0x001F +#define WDTCON_RMPS_SHIFT 0x0008 +#define WDTCON_ON BIT(15) +#define WDTCON_CLR_KEY 0x5743 + +/* Reset Control Register fields for watchdog */ +#define RESETCON_TIMEOUT_IDLE BIT(2) +#define RESETCON_TIMEOUT_SLEEP BIT(3) +#define RESETCON_WDT_TIMEOUT BIT(4) + +struct pic32_wdt { + void __iomem *regs; + void __iomem *rst_base; + struct clk *clk; +}; + +static inline bool pic32_wdt_is_win_enabled(struct pic32_wdt *wdt) +{ + return !!(readl(wdt->regs + WDTCON_REG) & WDTCON_WIN_EN); +} + +static inline u32 pic32_wdt_get_post_scaler(struct pic32_wdt *wdt) +{ + u32 v = readl(wdt->regs + WDTCON_REG); + + return (v >> WDTCON_RMPS_SHIFT) & WDTCON_RMPS_MASK; +} + +static inline u32 pic32_wdt_get_clk_id(struct pic32_wdt *wdt) +{ + u32 v = readl(wdt->regs + WDTCON_REG); + + return (v >> WDTCON_RMCS_SHIFT) & WDTCON_RMCS_MASK; +} + +static int pic32_wdt_bootstatus(struct pic32_wdt *wdt) +{ + u32 v = readl(wdt->rst_base); + + writel(RESETCON_WDT_TIMEOUT, PIC32_CLR(wdt->rst_base)); + + return v & RESETCON_WDT_TIMEOUT; +} + +static u32 pic32_wdt_get_timeout_secs(struct pic32_wdt *wdt, struct device *dev) +{ + unsigned long rate; + u32 period, ps, terminal; + + rate = clk_get_rate(wdt->clk); + + dev_dbg(dev, "wdt: clk_id %d, clk_rate %lu (prescale)\n", + pic32_wdt_get_clk_id(wdt), rate); + + /* default, prescaler of 32 (i.e. div-by-32) is implicit. */ + rate >>= 5; + if (!rate) + return 0; + + /* calculate terminal count from postscaler. */ + ps = pic32_wdt_get_post_scaler(wdt); + terminal = BIT(ps); + + /* find time taken (in secs) to reach terminal count */ + period = terminal / rate; + dev_dbg(dev, + "wdt: clk_rate %lu (postscale) / terminal %d, timeout %dsec\n", + rate, terminal, period); + + return period; +} + +static void pic32_wdt_keepalive(struct pic32_wdt *wdt) +{ + /* write key through single half-word */ + writew(WDTCON_CLR_KEY, wdt->regs + WDTCON_REG + 2); +} + +static int pic32_wdt_start(struct watchdog_device *wdd) +{ + struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); + + writel(WDTCON_ON, PIC32_SET(wdt->regs + WDTCON_REG)); + pic32_wdt_keepalive(wdt); + + return 0; +} + +static int pic32_wdt_stop(struct watchdog_device *wdd) +{ + struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); + + writel(WDTCON_ON, PIC32_CLR(wdt->regs + WDTCON_REG)); + + /* + * Cannot touch registers in the CPU cycle following clearing the + * ON bit. + */ + nop(); + + return 0; +} + +static int pic32_wdt_ping(struct watchdog_device *wdd) +{ + struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); + + pic32_wdt_keepalive(wdt); + + return 0; +} + +static const struct watchdog_ops pic32_wdt_fops = { + .owner = THIS_MODULE, + .start = pic32_wdt_start, + .stop = pic32_wdt_stop, + .ping = pic32_wdt_ping, +}; + +static const struct watchdog_info pic32_wdt_ident = { + .options = WDIOF_KEEPALIVEPING | + WDIOF_MAGICCLOSE | WDIOF_CARDRESET, + .identity = "PIC32 Watchdog", +}; + +static struct watchdog_device pic32_wdd = { + .info = &pic32_wdt_ident, + .ops = &pic32_wdt_fops, +}; + +static const struct of_device_id pic32_wdt_dt_ids[] = { + { .compatible = "microchip,pic32mzda-wdt", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, pic32_wdt_dt_ids); + +static void pic32_clk_disable_unprepare(void *data) +{ + clk_disable_unprepare(data); +} + +static int pic32_wdt_drv_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + int ret; + struct watchdog_device *wdd = &pic32_wdd; + struct pic32_wdt *wdt; + + wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); + if (!wdt) + return -ENOMEM; + + wdt->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(wdt->regs)) + return PTR_ERR(wdt->regs); + + wdt->rst_base = devm_ioremap(dev, PIC32_BASE_RESET, 0x10); + if (!wdt->rst_base) + return -ENOMEM; + + wdt->clk = devm_clk_get(dev, NULL); + if (IS_ERR(wdt->clk)) { + dev_err(dev, "clk not found\n"); + return PTR_ERR(wdt->clk); + } + + ret = clk_prepare_enable(wdt->clk); + if (ret) { + dev_err(dev, "clk enable failed\n"); + return ret; + } + ret = devm_add_action_or_reset(dev, pic32_clk_disable_unprepare, + wdt->clk); + if (ret) + return ret; + + if (pic32_wdt_is_win_enabled(wdt)) { + dev_err(dev, "windowed-clear mode is not supported.\n"); + return -ENODEV; + } + + wdd->timeout = pic32_wdt_get_timeout_secs(wdt, dev); + if (!wdd->timeout) { + dev_err(dev, "failed to read watchdog register timeout\n"); + return -EINVAL; + } + + dev_info(dev, "timeout %d\n", wdd->timeout); + + wdd->bootstatus = pic32_wdt_bootstatus(wdt) ? WDIOF_CARDRESET : 0; + + watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT); + watchdog_set_drvdata(wdd, wdt); + + ret = devm_watchdog_register_device(dev, wdd); + if (ret) + return ret; + + platform_set_drvdata(pdev, wdd); + + return 0; +} + +static struct platform_driver pic32_wdt_driver = { + .probe = pic32_wdt_drv_probe, + .driver = { + .name = "pic32-wdt", + .of_match_table = of_match_ptr(pic32_wdt_dt_ids), + } +}; + +module_platform_driver(pic32_wdt_driver); + +MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>"); +MODULE_DESCRIPTION("Microchip PIC32 Watchdog Timer"); +MODULE_LICENSE("GPL"); |