/* * PIC32 watchdog driver * * Joshua Henderson * Copyright (c) 2016, Microchip Technology Inc. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #include #include #include /* 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 int pic32_wdt_drv_probe(struct platform_device *pdev) { int ret; struct watchdog_device *wdd = &pic32_wdd; struct pic32_wdt *wdt; struct resource *mem; wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); if (!wdt) return -ENOMEM; mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); wdt->regs = devm_ioremap_resource(&pdev->dev, mem); if (IS_ERR(wdt->regs)) return PTR_ERR(wdt->regs); wdt->rst_base = devm_ioremap(&pdev->dev, PIC32_BASE_RESET, 0x10); if (!wdt->rst_base) return -ENOMEM; wdt->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(wdt->clk)) { dev_err(&pdev->dev, "clk not found\n"); return PTR_ERR(wdt->clk); } ret = clk_prepare_enable(wdt->clk); if (ret) { dev_err(&pdev->dev, "clk enable failed\n"); return ret; } if (pic32_wdt_is_win_enabled(wdt)) { dev_err(&pdev->dev, "windowed-clear mode is not supported.\n"); ret = -ENODEV; goto out_disable_clk; } wdd->timeout = pic32_wdt_get_timeout_secs(wdt, &pdev->dev); if (!wdd->timeout) { dev_err(&pdev->dev, "failed to read watchdog register timeout\n"); ret = -EINVAL; goto out_disable_clk; } dev_info(&pdev->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 = watchdog_register_device(wdd); if (ret) { dev_err(&pdev->dev, "watchdog register failed, err %d\n", ret); goto out_disable_clk; } platform_set_drvdata(pdev, wdd); return 0; out_disable_clk: clk_disable_unprepare(wdt->clk); return ret; } static int pic32_wdt_drv_remove(struct platform_device *pdev) { struct watchdog_device *wdd = platform_get_drvdata(pdev); struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); watchdog_unregister_device(wdd); clk_disable_unprepare(wdt->clk); return 0; } static struct platform_driver pic32_wdt_driver = { .probe = pic32_wdt_drv_probe, .remove = pic32_wdt_drv_remove, .driver = { .name = "pic32-wdt", .of_match_table = of_match_ptr(pic32_wdt_dt_ids), } }; module_platform_driver(pic32_wdt_driver); MODULE_AUTHOR("Joshua Henderson "); MODULE_DESCRIPTION("Microchip PIC32 Watchdog Timer"); MODULE_LICENSE("GPL");