diff options
Diffstat (limited to 'drivers/watchdog/pic32-dmt.c')
| -rw-r--r-- | drivers/watchdog/pic32-dmt.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/drivers/watchdog/pic32-dmt.c b/drivers/watchdog/pic32-dmt.c new file mode 100644 index 000000000..c797305f8 --- /dev/null +++ b/drivers/watchdog/pic32-dmt.c @@ -0,0 +1,256 @@ +/* + * PIC32 deadman timer driver + * + * Purna Chandra Mandal <purna.mandal@microchip.com> + * 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 <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> + +/* Deadman Timer Regs */ +#define DMTCON_REG 0x00 +#define DMTPRECLR_REG 0x10 +#define DMTCLR_REG 0x20 +#define DMTSTAT_REG 0x30 +#define DMTCNT_REG 0x40 +#define DMTPSCNT_REG 0x60 +#define DMTPSINTV_REG 0x70 + +/* Deadman Timer Regs fields */ +#define DMT_ON BIT(15) +#define DMT_STEP1_KEY BIT(6) +#define DMT_STEP2_KEY BIT(3) +#define DMTSTAT_WINOPN BIT(0) +#define DMTSTAT_EVENT BIT(5) +#define DMTSTAT_BAD2 BIT(6) +#define DMTSTAT_BAD1 BIT(7) + +/* Reset Control Register fields for watchdog */ +#define RESETCON_DMT_TIMEOUT BIT(5) + +struct pic32_dmt { + void __iomem *regs; + struct clk *clk; +}; + +static inline void dmt_enable(struct pic32_dmt *dmt) +{ + writel(DMT_ON, PIC32_SET(dmt->regs + DMTCON_REG)); +} + +static inline void dmt_disable(struct pic32_dmt *dmt) +{ + writel(DMT_ON, PIC32_CLR(dmt->regs + DMTCON_REG)); + /* + * Cannot touch registers in the CPU cycle following clearing the + * ON bit. + */ + nop(); +} + +static inline int dmt_bad_status(struct pic32_dmt *dmt) +{ + u32 val; + + val = readl(dmt->regs + DMTSTAT_REG); + val &= (DMTSTAT_BAD1 | DMTSTAT_BAD2 | DMTSTAT_EVENT); + if (val) + return -EAGAIN; + + return 0; +} + +static inline int dmt_keepalive(struct pic32_dmt *dmt) +{ + u32 v; + u32 timeout = 500; + + /* set pre-clear key */ + writel(DMT_STEP1_KEY << 8, dmt->regs + DMTPRECLR_REG); + + /* wait for DMT window to open */ + while (--timeout) { + v = readl(dmt->regs + DMTSTAT_REG) & DMTSTAT_WINOPN; + if (v == DMTSTAT_WINOPN) + break; + } + + /* apply key2 */ + writel(DMT_STEP2_KEY, dmt->regs + DMTCLR_REG); + + /* check whether keys are latched correctly */ + return dmt_bad_status(dmt); +} + +static inline u32 pic32_dmt_get_timeout_secs(struct pic32_dmt *dmt) +{ + unsigned long rate; + + rate = clk_get_rate(dmt->clk); + if (rate) + return readl(dmt->regs + DMTPSCNT_REG) / rate; + + return 0; +} + +static inline u32 pic32_dmt_bootstatus(struct pic32_dmt *dmt) +{ + u32 v; + void __iomem *rst_base; + + rst_base = ioremap(PIC32_BASE_RESET, 0x10); + if (!rst_base) + return 0; + + v = readl(rst_base); + + writel(RESETCON_DMT_TIMEOUT, PIC32_CLR(rst_base)); + + iounmap(rst_base); + return v & RESETCON_DMT_TIMEOUT; +} + +static int pic32_dmt_start(struct watchdog_device *wdd) +{ + struct pic32_dmt *dmt = watchdog_get_drvdata(wdd); + + dmt_enable(dmt); + return dmt_keepalive(dmt); +} + +static int pic32_dmt_stop(struct watchdog_device *wdd) +{ + struct pic32_dmt *dmt = watchdog_get_drvdata(wdd); + + dmt_disable(dmt); + + return 0; +} + +static int pic32_dmt_ping(struct watchdog_device *wdd) +{ + struct pic32_dmt *dmt = watchdog_get_drvdata(wdd); + + return dmt_keepalive(dmt); +} + +static const struct watchdog_ops pic32_dmt_fops = { + .owner = THIS_MODULE, + .start = pic32_dmt_start, + .stop = pic32_dmt_stop, + .ping = pic32_dmt_ping, +}; + +static const struct watchdog_info pic32_dmt_ident = { + .options = WDIOF_KEEPALIVEPING | + WDIOF_MAGICCLOSE, + .identity = "PIC32 Deadman Timer", +}; + +static struct watchdog_device pic32_dmt_wdd = { + .info = &pic32_dmt_ident, + .ops = &pic32_dmt_fops, +}; + +static int pic32_dmt_probe(struct platform_device *pdev) +{ + int ret; + struct pic32_dmt *dmt; + struct resource *mem; + struct watchdog_device *wdd = &pic32_dmt_wdd; + + dmt = devm_kzalloc(&pdev->dev, sizeof(*dmt), GFP_KERNEL); + if (!dmt) + return -ENOMEM; + + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); + dmt->regs = devm_ioremap_resource(&pdev->dev, mem); + if (IS_ERR(dmt->regs)) + return PTR_ERR(dmt->regs); + + dmt->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(dmt->clk)) { + dev_err(&pdev->dev, "clk not found\n"); + return PTR_ERR(dmt->clk); + } + + ret = clk_prepare_enable(dmt->clk); + if (ret) + return ret; + + wdd->timeout = pic32_dmt_get_timeout_secs(dmt); + 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_dmt_bootstatus(dmt) ? WDIOF_CARDRESET : 0; + + watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT); + watchdog_set_drvdata(wdd, dmt); + + 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(dmt->clk); + return ret; +} + +static int pic32_dmt_remove(struct platform_device *pdev) +{ + struct watchdog_device *wdd = platform_get_drvdata(pdev); + struct pic32_dmt *dmt = watchdog_get_drvdata(wdd); + + watchdog_unregister_device(wdd); + clk_disable_unprepare(dmt->clk); + + return 0; +} + +static const struct of_device_id pic32_dmt_of_ids[] = { + { .compatible = "microchip,pic32mzda-dmt",}, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, pic32_dmt_of_ids); + +static struct platform_driver pic32_dmt_driver = { + .probe = pic32_dmt_probe, + .remove = pic32_dmt_remove, + .driver = { + .name = "pic32-dmt", + .of_match_table = of_match_ptr(pic32_dmt_of_ids), + } +}; + +module_platform_driver(pic32_dmt_driver); + +MODULE_AUTHOR("Purna Chandra Mandal <purna.mandal@microchip.com>"); +MODULE_DESCRIPTION("Microchip PIC32 DMT Driver"); +MODULE_LICENSE("GPL"); |