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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@aj.id.au>
Tested-by: Matt Spinler <mspinler@linux.vnet.ibm.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Andrew Jeffery 2017-08-02 14:15:29 +09:30 committed by Wim Van Sebroeck
parent e654f19165
commit 012c04601f
1 changed files with 102 additions and 3 deletions
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105
drivers/watchdog/aspeed_wdt.c
View File

@ -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");