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Message-Id: <20170802044529.30032-3-andrew@aj.id.au>
Date: Wed, 2 Aug 2017 14:15:29 +0930
From: Andrew Jeffery <andrew@...id.au>
To: linux-watchdog@...r.kernel.org
Cc: Andrew Jeffery <andrew@...id.au>, wim@...ana.be,
linux@...ck-us.net, robh+dt@...nel.org, mark.rutland@....com,
joel@....id.au, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-aspeed@...ts.ozlabs.org,
openbmc@...ts.ozlabs.org
Subject: [PATCH 2/2] 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 <andrew@...id.au>
Tested-by: Matt Spinler <mspinler@...ux.vnet.ibm.com>
---
drivers/watchdog/aspeed_wdt.c | 105 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 102 insertions(+), 3 deletions(-)
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");
--
2.11.0
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