From 012c04601f9dc6a268ebff87a890b339af6d25bf Mon Sep 17 00:00:00 2001 From: Andrew Jeffery Date: Wed, 2 Aug 2017 14:15:29 +0930 Subject: watchdog: aspeed: Support configuration of external signal properties Add support for configuring the drive strength and polarity on the AST2500, and the pulse duration on both the AST2400 and AST2500. Signed-off-by: Andrew Jeffery Tested-by: Matt Spinler Reviewed-by: Guenter Roeck Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/aspeed_wdt.c | 105 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 102 insertions(+), 3 deletions(-) (limited to 'drivers/watchdog/aspeed_wdt.c') diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c index c707ab647922..79cc766cd30f 100644 --- a/drivers/watchdog/aspeed_wdt.c +++ b/drivers/watchdog/aspeed_wdt.c @@ -23,9 +23,21 @@ struct aspeed_wdt { u32 ctrl; }; +struct aspeed_wdt_config { + u32 ext_pulse_width_mask; +}; + +static const struct aspeed_wdt_config ast2400_config = { + .ext_pulse_width_mask = 0xff, +}; + +static const struct aspeed_wdt_config ast2500_config = { + .ext_pulse_width_mask = 0xfffff, +}; + static const struct of_device_id aspeed_wdt_of_table[] = { - { .compatible = "aspeed,ast2400-wdt" }, - { .compatible = "aspeed,ast2500-wdt" }, + { .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config }, + { .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config }, { }, }; MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table); @@ -43,6 +55,38 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table); #define WDT_CTRL_RESET_SYSTEM BIT(1) #define WDT_CTRL_ENABLE BIT(0) +/* + * WDT_RESET_WIDTH controls the characteristics of the external pulse (if + * enabled), specifically: + * + * * Pulse duration + * * Drive mode: push-pull vs open-drain + * * Polarity: Active high or active low + * + * Pulse duration configuration is available on both the AST2400 and AST2500, + * though the field changes between SoCs: + * + * AST2400: Bits 7:0 + * AST2500: Bits 19:0 + * + * This difference is captured in struct aspeed_wdt_config. + * + * The AST2500 exposes the drive mode and polarity options, but not in a + * regular fashion. For read purposes, bit 31 represents active high or low, + * and bit 30 represents push-pull or open-drain. With respect to write, magic + * values need to be written to the top byte to change the state of the drive + * mode and polarity bits. Any other value written to the top byte has no + * effect on the state of the drive mode or polarity bits. However, the pulse + * width value must be preserved (as desired) if written. + */ +#define WDT_RESET_WIDTH 0x18 +#define WDT_RESET_WIDTH_ACTIVE_HIGH BIT(31) +#define WDT_ACTIVE_HIGH_MAGIC (0xA5 << 24) +#define WDT_ACTIVE_LOW_MAGIC (0x5A << 24) +#define WDT_RESET_WIDTH_PUSH_PULL BIT(30) +#define WDT_PUSH_PULL_MAGIC (0xA8 << 24) +#define WDT_OPEN_DRAIN_MAGIC (0x8A << 24) + #define WDT_RESTART_MAGIC 0x4755 /* 32 bits at 1MHz, in milliseconds */ @@ -139,10 +183,13 @@ static const struct watchdog_info aspeed_wdt_info = { static int aspeed_wdt_probe(struct platform_device *pdev) { + const struct aspeed_wdt_config *config; + const struct of_device_id *ofdid; struct aspeed_wdt *wdt; struct resource *res; struct device_node *np; const char *reset_type; + u32 duration; int ret; wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); @@ -167,13 +214,19 @@ static int aspeed_wdt_probe(struct platform_device *pdev) wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT; watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev); + np = pdev->dev.of_node; + + ofdid = of_match_node(aspeed_wdt_of_table, np); + if (!ofdid) + return -EINVAL; + config = ofdid->data; + wdt->ctrl = WDT_CTRL_1MHZ_CLK; /* * Control reset on a per-device basis to ensure the * host is not affected by a BMC reboot */ - np = pdev->dev.of_node; ret = of_property_read_string(np, "aspeed,reset-type", &reset_type); if (ret) { wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM; @@ -197,6 +250,52 @@ static int aspeed_wdt_probe(struct platform_device *pdev) set_bit(WDOG_HW_RUNNING, &wdt->wdd.status); } + if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) { + u32 reg = readl(wdt->base + WDT_RESET_WIDTH); + + reg &= config->ext_pulse_width_mask; + if (of_property_read_bool(np, "aspeed,ext-push-pull")) + reg |= WDT_PUSH_PULL_MAGIC; + else + reg |= WDT_OPEN_DRAIN_MAGIC; + + writel(reg, wdt->base + WDT_RESET_WIDTH); + + reg &= config->ext_pulse_width_mask; + if (of_property_read_bool(np, "aspeed,ext-active-high")) + reg |= WDT_ACTIVE_HIGH_MAGIC; + else + reg |= WDT_ACTIVE_LOW_MAGIC; + + writel(reg, wdt->base + WDT_RESET_WIDTH); + } + + if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) { + u32 max_duration = config->ext_pulse_width_mask + 1; + + if (duration == 0 || duration > max_duration) { + dev_err(&pdev->dev, "Invalid pulse duration: %uus\n", + duration); + duration = max(1U, min(max_duration, duration)); + dev_info(&pdev->dev, "Pulse duration set to %uus\n", + duration); + } + + /* + * The watchdog is always configured with a 1MHz source, so + * there is no need to scale the microsecond value. However we + * need to offset it - from the datasheet: + * + * "This register decides the asserting duration of wdt_ext and + * wdt_rstarm signal. The default value is 0xFF. It means the + * default asserting duration of wdt_ext and wdt_rstarm is + * 256us." + * + * This implies a value of 0 gives a 1us pulse. + */ + writel(duration - 1, wdt->base + WDT_RESET_WIDTH); + } + ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd); if (ret) { dev_err(&pdev->dev, "failed to register\n"); -- cgit v1.2.3