[PATCH 3/3] power: reset: at91-shdwc: add new shutdown controller driver

[Nicolas Ferre]

Sama5d2 SoC has a completely new shutdown controller with new features and
register layout. It thus makes sense to add a new driver for this new
peripheral.

This driver is Device Tree only and handles events from the wake-up pin and
the RTC.
As the register layout may change in the future, so some values are encoded
in a configuration structure.

Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
---
 drivers/power/reset/Kconfig      |   8 ++
 drivers/power/reset/Makefile     |   1 +
 drivers/power/reset/at91-shdwc.c | 263 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 272 insertions(+)
 create mode 100644 drivers/power/reset/at91-shdwc.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 5a0189bf19bb..7f52bc938795 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -30,6 +30,14 @@ config POWER_RESET_AT91_RESET
 	  This driver supports restart for Atmel AT91SAM9 and SAMA5
 	  SoCs
 
+config POWER_RESET_AT91_SHDWC
+	bool "Atmel AT91 shutdown controller driver"
+	depends on ARCH_AT91
+	default SOC_SAMA5
+	help
+	  This driver supports poweroff for some Atmel SAMA5 SoCs. It is
+	  present for example on SAMA5D2 SoC.
+
 config POWER_RESET_AXXIA
 	bool "LSI Axxia reset driver"
 	depends on ARCH_AXXIA
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 096fa67047f6..6b9020ed3fb7 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -1,6 +1,7 @@
 obj-$(CONFIG_POWER_RESET_AS3722) += as3722-poweroff.o
 obj-$(CONFIG_POWER_RESET_AT91_POWEROFF) += at91-poweroff.o
 obj-$(CONFIG_POWER_RESET_AT91_RESET) += at91-reset.o
+obj-$(CONFIG_POWER_RESET_AT91_SHDWC) += at91-shdwc.o
 obj-$(CONFIG_POWER_RESET_AXXIA) += axxia-reset.o
 obj-$(CONFIG_POWER_RESET_BRCMSTB) += brcmstb-reboot.o
 obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
diff --git a/drivers/power/reset/at91-shdwc.c b/drivers/power/reset/at91-shdwc.c
new file mode 100644
index 000000000000..bc5cbf2bc95b
--- /dev/null
+++ b/drivers/power/reset/at91-shdwc.c
@@ -0,0 +1,263 @@
+/*
+ * Atmel Shutdown Controller (SHDWC) driver
+ *
+ * Copyright (C) 2015 Atmel Corporation,
+ *                    Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
+ *
+ * Evolved from driver at91-poweroff.c.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * TODO:
+ * - addition to status of other wake-up inputs [1 - 15]
+ * - Analog Comparator wake-up alarm
+ * - Serial RX wake-up alarm
+ * - low power debouncer
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+
+#define SLOW_CLOCK_FREQ	32768
+
+#define AT91_SHDW_CR	0x00		/* Shut Down Control Register */
+#define AT91_SHDW_SHDW		BIT(0)			/* Shut Down command */
+#define AT91_SHDW_KEY		(0xa5 << 24)		/* KEY Password */
+
+#define AT91_SHDW_MR	0x04		/* Shut Down Mode Register */
+#define AT91_SHDW_WKUPDBC_SHIFT	24
+#define AT91_SHDW_WKUPDBC_MASK	GENMASK(31, 16)
+#define AT91_SHDW_WKUPDBC(x)	(((x) << AT91_SHDW_WKUPDBC_SHIFT) \
+						& AT91_SHDW_WKUPDBC_MASK)
+
+#define AT91_SHDW_SR	0x08		/* Shut Down Status Register */
+#define AT91_SHDW_WKUPIS_SHIFT	16
+#define AT91_SHDW_WKUPIS_MASK	GENMASK(31, 16)
+#define AT91_SHDW_WKUPIS(x)	((1 << (x)) << AT91_SHDW_WKUPIS_SHIFT \
+						& AT91_SHDW_WKUPIS_MASK)
+
+#define AT91_SHDW_WUIR	0x0c		/* Shutdown Wake-up Inputs Register */
+#define AT91_SHDW_WKUPEN_MASK	GENMASK(15, 0)
+#define AT91_SHDW_WKUPEN(x)	((1 << (x)) & AT91_SHDW_WKUPEN_MASK)
+#define AT91_SHDW_WKUPT_SHIFT	16
+#define AT91_SHDW_WKUPT_MASK	GENMASK(31, 16)
+#define AT91_SHDW_WKUPT(x)	((1 << (x)) << AT91_SHDW_WKUPT_SHIFT \
+						& AT91_SHDW_WKUPT_MASK)
+
+#define SHDW_WK_PIN(reg, cfg)	((reg) & AT91_SHDW_WKUPIS((cfg)->wkup_pin_input))
+#define SHDW_RTCWK(reg, cfg)	(((reg) >> ((cfg)->sr_rtcwk_shift)) & 0x1)
+#define SHDW_RTCWKEN(cfg)	(1 << ((cfg)->mr_rtcwk_shift))
+
+#define DBC_PERIOD_US(x)	DIV_ROUND_UP_ULL((1000000 * (x)), \
+							SLOW_CLOCK_FREQ)
+
+struct shdwc_config {
+	u8 wkup_pin_input;
+        u8 mr_rtcwk_shift;
+        u8 sr_rtcwk_shift;
+};
+
+struct shdwc {
+	struct shdwc_config *cfg;
+	void __iomem *at91_shdwc_base;
+};
+
+/*
+ * Hold configuration here, cannot be more than one instance of the driver
+ * since pm_power_off itself is global.
+ */
+static struct shdwc *at91_shdwc;
+
+static const unsigned long long sdwc_dbc_period[] = {
+	0, 3, 32, 512, 4096, 32768,
+};
+
+static void __init at91_wakeup_status(struct platform_device *pdev)
+{
+	struct shdwc *shdw = platform_get_drvdata(pdev);
+	u32 reg;
+	char *reason = "unknown";
+
+	reg = readl(shdw->at91_shdwc_base + AT91_SHDW_SR);
+
+	dev_dbg(&pdev->dev, "%s: status = %#x\n", __func__, reg);
+
+	/* Simple power-on, just bail out */
+	if (!reg)
+		return;
+
+	if (SHDW_WK_PIN(reg, shdw->cfg))
+		reason = "WKUP pin";
+        else if (SHDW_RTCWK(reg, shdw->cfg))
+		reason = "RTC";
+
+	pr_info("AT91: Wake-Up source: %s\n", reason);
+}
+
+static void at91_poweroff(void)
+{
+	BUG_ON(!at91_shdwc);
+
+	writel(AT91_SHDW_KEY | AT91_SHDW_SHDW,
+			at91_shdwc->at91_shdwc_base + AT91_SHDW_CR);
+}
+
+static u32 at91_shdwc_debouncer_value(struct platform_device *pdev,
+				      u32 in_period_us)
+{
+	int i;
+	int max_idx = ARRAY_SIZE(sdwc_dbc_period) - 1;
+	unsigned long long period_us;
+	unsigned long long max_period_us = DBC_PERIOD_US(sdwc_dbc_period[max_idx]);
+
+	if (in_period_us > max_period_us) {
+		dev_warn(&pdev->dev,
+			 "debouncer period %u too big, reduced to %llu us\n",
+			 in_period_us, max_period_us);
+		return max_idx;
+	}
+
+	for (i = max_idx - 1; i > 0; i--) {
+		period_us = DBC_PERIOD_US(sdwc_dbc_period[i]);
+		dev_dbg(&pdev->dev, "%s: ref[%d] = %llu\n",
+						__func__, i, period_us);
+		if (in_period_us > period_us)
+			break;
+	}
+
+	return i + 1;
+}
+
+static u32 at91_shdwc_get_wakeup_input(struct platform_device *pdev,
+				       struct device_node *np)
+{
+	struct device_node *cnp;
+	const char *pm;
+	u32 wk_input_mask;
+	u32 wuir = 0;
+	u32 wk_input;
+
+	for_each_child_of_node(np, cnp) {
+		if (of_property_read_u32(cnp, "reg", &wk_input)) {
+			dev_warn(&pdev->dev, "reg property is missing for %s\n",
+				 cnp->full_name);
+			continue;
+		}
+
+		wk_input_mask = 1 << wk_input;
+		if (!(wk_input_mask & AT91_SHDW_WKUPEN_MASK)) {
+			dev_warn(&pdev->dev,
+				 "wake-up input %d out of bounds ignore\n",
+				 wk_input);
+			continue;
+		}
+		wuir |= wk_input_mask;
+
+		if (!of_property_read_string(cnp, "atmel,wakeup-type", &pm)) {
+			if (!strcasecmp(pm, "high"))
+				/*
+				 * only add a type if "high" is specified. Low
+				 * is the default.
+				 */
+				wuir |= AT91_SHDW_WKUPT(wk_input);
+		}
+		dev_dbg(&pdev->dev, "%s: (child %d) wuir = %#x\n",
+						__func__, wk_input, wuir);
+	}
+
+	return wuir;
+}
+
+static void at91_shdwc_dt_configure(struct platform_device *pdev)
+{
+	struct shdwc *shdw = platform_get_drvdata(pdev);
+	struct device_node *np = pdev->dev.of_node;
+	u32 mode = 0, tmp, input;
+
+	if (!np) {
+		dev_err(&pdev->dev, "device node not found\n");
+		return;
+	}
+
+	if (!of_property_read_u32(np, "atmel,shdwc-debouncer", &tmp)) {
+		mode |= AT91_SHDW_WKUPDBC(at91_shdwc_debouncer_value(pdev, tmp));
+	}
+
+	if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
+			mode |= SHDW_RTCWKEN(shdw->cfg);
+
+	dev_dbg(&pdev->dev, "%s: mode = %#x\n", __func__, mode);
+	writel(mode, shdw->at91_shdwc_base + AT91_SHDW_MR);
+
+	input = at91_shdwc_get_wakeup_input(pdev, np);
+	writel(input, shdw->at91_shdwc_base + AT91_SHDW_WUIR);
+}
+
+static const struct shdwc_config sama5d2_shdwc_config = {
+	.wkup_pin_input = 0,
+	.mr_rtcwk_shift = 17,
+	.sr_rtcwk_shift = 5,
+};
+
+static struct of_device_id at91_shdwc_of_match[] = {
+	{
+		.compatible = "atmel,sama5d2-shdwc",
+                .data = &sama5d2_shdwc_config,
+	}, {
+		/*sentinel*/
+	}
+};
+
+static int at91_shdwc_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	const struct of_device_id *match;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	at91_shdwc = devm_kzalloc(&pdev->dev, sizeof(*at91_shdwc), GFP_KERNEL);
+	if (!at91_shdwc)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, at91_shdwc);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	at91_shdwc->at91_shdwc_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(at91_shdwc->at91_shdwc_base)) {
+		dev_err(&pdev->dev, "Could not map reset controller address\n");
+		return PTR_ERR(at91_shdwc->at91_shdwc_base);
+	}
+
+	match = of_match_node(at91_shdwc_of_match, pdev->dev.of_node);
+	if (match != NULL)
+		at91_shdwc->cfg = (struct shdwc_config *)(match->data);
+	else
+		return -ENODATA;
+
+	at91_wakeup_status(pdev);
+
+	at91_shdwc_dt_configure(pdev);
+
+	pm_power_off = at91_poweroff;
+
+	return 0;
+}
+
+static struct platform_driver at91_shdwc_driver = {
+	.probe = at91_shdwc_probe,
+	.driver = {
+		.name = "at91-shdwc",
+		.of_match_table = at91_shdwc_of_match,
+	},
+};
+module_platform_driver(at91_shdwc_driver);
+
+MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@xxxxxxxxx>");
+MODULE_DESCRIPTION("Atmel shutdown controller driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.3

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