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Release 4.10 drivers/watchdog/pic32-wdt.c

Directory: drivers/watchdog
/*
 * PIC32 watchdog driver
 *
 * Joshua Henderson <joshua.henderson@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>

/* 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); }

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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; }

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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; }

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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; }

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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; }

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static void pic32_wdt_keepalive(struct pic32_wdt *wdt) { /* write key through single half-word */ writew(WDTCON_CLR_KEY, wdt->regs + WDTCON_REG + 2); }

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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; }

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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; }

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static int pic32_wdt_ping(struct watchdog_device *wdd) { struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); pic32_wdt_keepalive(wdt); return 0; }

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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; }

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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; }

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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 <joshua.henderson@microchip.com>"); MODULE_DESCRIPTION("Microchip PIC32 Watchdog Timer"); MODULE_LICENSE("GPL");

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Directory: drivers/watchdog
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