drivers/power/reset/at91-sama5d2_shdwc.c - linux - Git at Google

 /*
  * Atmel SAMA5D2-Compatible Shutdown Controller (SHDWC) driver.
  * Found on some SoCs as the sama5d2 (obviously).
  *
  * Copyright (C) 2015 Atmel Corporation,
  *                    Nicolas Ferre <nicolas.ferre@atmel.com>
  *
  * 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/clk.h>
 #include <linux/clk/at91_pmc.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/printk.h>

 #include <soc/at91/at91sam9_ddrsdr.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		(0xa5UL << 24)		/* KEY Password */

 #define AT91_SHDW_MR	0x04		/* Shut Down Mode Register */
 #define AT91_SHDW_WKUPDBC_SHIFT	24
 #define AT91_SHDW_WKUPDBC_MASK	GENMASK(26, 24)
 #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_RTTWK(reg, cfg)	(((reg) >> ((cfg)->sr_rttwk_shift)) & 0x1)
 #define SHDW_RTCWKEN(cfg)	(1 << ((cfg)->mr_rtcwk_shift))
 #define SHDW_RTTWKEN(cfg)	(1 << ((cfg)->mr_rttwk_shift))

 #define DBC_PERIOD_US(x)	DIV_ROUND_UP_ULL((1000000 * (x)), \
 							SLOW_CLOCK_FREQ)

 #define SHDW_CFG_NOT_USED	(32)

 struct shdwc_reg_config {
 	u8 wkup_pin_input;
 	u8 mr_rtcwk_shift;
 	u8 mr_rttwk_shift;
 	u8 sr_rtcwk_shift;
 	u8 sr_rttwk_shift;
 };

 struct pmc_reg_config {
 	u8 mckr;
 };

 struct ddrc_reg_config {
 	u32 type_offset;
 	u32 type_mask;
 };

 struct reg_config {
 	struct shdwc_reg_config shdwc;
 	struct pmc_reg_config pmc;
 	struct ddrc_reg_config ddrc;
 };

 struct shdwc {
 	const struct reg_config *rcfg;
 	struct clk *sclk;
 	void __iomem *shdwc_base;
 	void __iomem *mpddrc_base;
 	void __iomem *pmc_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);
 	const struct reg_config *rcfg = shdw->rcfg;
 	u32 reg;
 	char *reason = "unknown";

 	reg = readl(shdw->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, &rcfg->shdwc))
 		reason = "WKUP pin";
 	else if (SHDW_RTCWK(reg, &rcfg->shdwc))
 		reason = "RTC";
 	else if (SHDW_RTTWK(reg, &rcfg->shdwc))
 		reason = "RTT";

 	pr_info("AT91: Wake-Up source: %s\n", reason);
 }

 static void at91_poweroff(void)
 {
 	asm volatile(
 		/* Align to cache lines */
 		".balign 32\n\t"

 		/* Ensure AT91_SHDW_CR is in the TLB by reading it */
 		"	ldr	r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"

 		/* Power down SDRAM0 */
 		"	tst	%0, #0\n\t"
 		"	beq	1f\n\t"
 		"	str	%1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"

 		/* Switch the master clock source to slow clock. */
 		"1:	ldr	r6, [%4, %5]\n\t"
 		"	bic	r6, r6,  #" __stringify(AT91_PMC_CSS) "\n\t"
 		"	str	r6, [%4, %5]\n\t"
 		/* Wait for clock switch. */
 		"2:	ldr	r6, [%4, #" __stringify(AT91_PMC_SR) "]\n\t"
 		"	tst	r6, #"	    __stringify(AT91_PMC_MCKRDY) "\n\t"
 		"	beq	2b\n\t"

 		/* Shutdown CPU */
 		"	str	%3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"

 		"	b	.\n\t"
 		:
 		: "r" (at91_shdwc->mpddrc_base),
 		  "r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
 		  "r" (at91_shdwc->shdwc_base),
 		  "r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW),
 		  "r" (at91_shdwc->pmc_base),
 		  "r" (at91_shdwc->rcfg->pmc.mckr)
 		: "r6");
 }

 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;
 	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 %pOF\n",
 				 cnp);
 			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_bool(cnp, "atmel,wakeup-active-high"))
 			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);
 	const struct reg_config *rcfg = shdw->rcfg;
 	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, "debounce-delay-us", &tmp))
 		mode |= AT91_SHDW_WKUPDBC(at91_shdwc_debouncer_value(pdev, tmp));

 	if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
 		mode |= SHDW_RTCWKEN(&rcfg->shdwc);

 	if (of_property_read_bool(np, "atmel,wakeup-rtt-timer"))
 		mode |= SHDW_RTTWKEN(&rcfg->shdwc);

 	dev_dbg(&pdev->dev, "%s: mode = %#x\n", __func__, mode);
 	writel(mode, shdw->shdwc_base + AT91_SHDW_MR);

 	input = at91_shdwc_get_wakeup_input(pdev, np);
 	writel(input, shdw->shdwc_base + AT91_SHDW_WUIR);
 }

 static const struct reg_config sama5d2_reg_config = {
 	.shdwc = {
 		.wkup_pin_input = 0,
 		.mr_rtcwk_shift = 17,
 		.mr_rttwk_shift	= SHDW_CFG_NOT_USED,
 		.sr_rtcwk_shift = 5,
 		.sr_rttwk_shift = SHDW_CFG_NOT_USED,
 	},
 	.pmc = {
 		.mckr		= 0x30,
 	},
 	.ddrc = {
 		.type_offset	= AT91_DDRSDRC_MDR,
 		.type_mask	= AT91_DDRSDRC_MD
 	},
 };

 static const struct reg_config sam9x60_reg_config = {
 	.shdwc = {
 		.wkup_pin_input = 0,
 		.mr_rtcwk_shift = 17,
 		.mr_rttwk_shift = 16,
 		.sr_rtcwk_shift = 5,
 		.sr_rttwk_shift = 4,
 	},
 	.pmc = {
 		.mckr		= 0x28,
 	},
 	.ddrc = {
 		.type_offset	= AT91_DDRSDRC_MDR,
 		.type_mask	= AT91_DDRSDRC_MD
 	},
 };

 static const struct reg_config sama7g5_reg_config = {
 	.shdwc = {
 		.wkup_pin_input = 0,
 		.mr_rtcwk_shift = 17,
 		.mr_rttwk_shift = 16,
 		.sr_rtcwk_shift = 5,
 		.sr_rttwk_shift = 4,
 	},
 	.pmc = {
 		.mckr		= 0x28,
 	},
 };

 static const struct of_device_id at91_shdwc_of_match[] = {
 	{
 		.compatible = "atmel,sama5d2-shdwc",
 		.data = &sama5d2_reg_config,
 	},
 	{
 		.compatible = "microchip,sam9x60-shdwc",
 		.data = &sam9x60_reg_config,
 	},
 	{
 		.compatible = "microchip,sama7g5-shdwc",
 		.data = &sama7g5_reg_config,
 	}, {
 		/*sentinel*/
 	}
 };
 MODULE_DEVICE_TABLE(of, at91_shdwc_of_match);

 static const struct of_device_id at91_pmc_ids[] = {
 	{ .compatible = "atmel,sama5d2-pmc" },
 	{ .compatible = "microchip,sam9x60-pmc" },
 	{ .compatible = "microchip,sama7g5-pmc" },
 	{ /* Sentinel. */ }
 };

 static int __init at91_shdwc_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	const struct of_device_id *match;
 	struct device_node *np;
 	u32 ddr_type;
 	int ret;

 	if (!pdev->dev.of_node)
 		return -ENODEV;

 	if (at91_shdwc)
 		return -EBUSY;

 	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->shdwc_base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(at91_shdwc->shdwc_base)) {
 		dev_err(&pdev->dev, "Could not map reset controller address\n");
 		return PTR_ERR(at91_shdwc->shdwc_base);
 	}

 	match = of_match_node(at91_shdwc_of_match, pdev->dev.of_node);
 	at91_shdwc->rcfg = match->data;

 	at91_shdwc->sclk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(at91_shdwc->sclk))
 		return PTR_ERR(at91_shdwc->sclk);

 	ret = clk_prepare_enable(at91_shdwc->sclk);
 	if (ret) {
 		dev_err(&pdev->dev, "Could not enable slow clock\n");
 		return ret;
 	}

 	at91_wakeup_status(pdev);

 	at91_shdwc_dt_configure(pdev);

 	np = of_find_matching_node(NULL, at91_pmc_ids);
 	if (!np) {
 		ret = -ENODEV;
 		goto clk_disable;
 	}

 	at91_shdwc->pmc_base = of_iomap(np, 0);
 	of_node_put(np);

 	if (!at91_shdwc->pmc_base) {
 		ret = -ENOMEM;
 		goto clk_disable;
 	}

 	if (at91_shdwc->rcfg->ddrc.type_mask) {
 		np = of_find_compatible_node(NULL, NULL,
 					     "atmel,sama5d3-ddramc");
 		if (!np) {
 			ret = -ENODEV;
 			goto unmap;
 		}

 		at91_shdwc->mpddrc_base = of_iomap(np, 0);
 		of_node_put(np);

 		if (!at91_shdwc->mpddrc_base) {
 			ret = -ENOMEM;
 			goto unmap;
 		}

 		ddr_type = readl(at91_shdwc->mpddrc_base +
 				 at91_shdwc->rcfg->ddrc.type_offset) &
 				 at91_shdwc->rcfg->ddrc.type_mask;
 		if (ddr_type != AT91_DDRSDRC_MD_LPDDR2 &&
 		    ddr_type != AT91_DDRSDRC_MD_LPDDR3) {
 			iounmap(at91_shdwc->mpddrc_base);
 			at91_shdwc->mpddrc_base = NULL;
 		}
 	}

 	pm_power_off = at91_poweroff;

 	return 0;

 unmap:
 	iounmap(at91_shdwc->pmc_base);
 clk_disable:
 	clk_disable_unprepare(at91_shdwc->sclk);

 	return ret;
 }

 static int __exit at91_shdwc_remove(struct platform_device *pdev)
 {
 	struct shdwc *shdw = platform_get_drvdata(pdev);

 	if (pm_power_off == at91_poweroff)
 		pm_power_off = NULL;

 	/* Reset values to disable wake-up features  */
 	writel(0, shdw->shdwc_base + AT91_SHDW_MR);
 	writel(0, shdw->shdwc_base + AT91_SHDW_WUIR);

 	if (shdw->mpddrc_base)
 		iounmap(shdw->mpddrc_base);
 	iounmap(shdw->pmc_base);

 	clk_disable_unprepare(shdw->sclk);

 	return 0;
 }

 static struct platform_driver at91_shdwc_driver = {
 	.remove = __exit_p(at91_shdwc_remove),
 	.driver = {
 		.name = "at91-shdwc",
 		.of_match_table = at91_shdwc_of_match,
 	},
 };
 module_platform_driver_probe(at91_shdwc_driver, at91_shdwc_probe);

 MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@atmel.com>");
 MODULE_DESCRIPTION("Atmel shutdown controller driver");
 MODULE_LICENSE("GPL v2");
	/*
	* Atmel SAMA5D2-Compatible Shutdown Controller (SHDWC) driver.
	* Found on some SoCs as the sama5d2 (obviously).
	*
	* Copyright (C) 2015 Atmel Corporation,
	* Nicolas Ferre <nicolas.ferre@atmel.com>
	*
	* 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/clk.h>
	#include <linux/clk/at91_pmc.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_address.h>
	#include <linux/platform_device.h>
	#include <linux/printk.h>

	#include <soc/at91/at91sam9_ddrsdr.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 (0xa5UL << 24) /* KEY Password */

	#define AT91_SHDW_MR 0x04 /* Shut Down Mode Register */
	#define AT91_SHDW_WKUPDBC_SHIFT 24
	#define AT91_SHDW_WKUPDBC_MASK GENMASK(26, 24)
	#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_RTTWK(reg, cfg) (((reg) >> ((cfg)->sr_rttwk_shift)) & 0x1)
	#define SHDW_RTCWKEN(cfg) (1 << ((cfg)->mr_rtcwk_shift))
	#define SHDW_RTTWKEN(cfg) (1 << ((cfg)->mr_rttwk_shift))

	#define DBC_PERIOD_US(x) DIV_ROUND_UP_ULL((1000000 * (x)), \
	SLOW_CLOCK_FREQ)

	#define SHDW_CFG_NOT_USED (32)

	struct shdwc_reg_config {
	u8 wkup_pin_input;
	u8 mr_rtcwk_shift;
	u8 mr_rttwk_shift;
	u8 sr_rtcwk_shift;
	u8 sr_rttwk_shift;
	};

	struct pmc_reg_config {
	u8 mckr;
	};

	struct ddrc_reg_config {
	u32 type_offset;
	u32 type_mask;
	};

	struct reg_config {
	struct shdwc_reg_config shdwc;
	struct pmc_reg_config pmc;
	struct ddrc_reg_config ddrc;
	};

	struct shdwc {
	const struct reg_config *rcfg;
	struct clk *sclk;
	void __iomem *shdwc_base;
	void __iomem *mpddrc_base;
	void __iomem *pmc_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);
	const struct reg_config *rcfg = shdw->rcfg;
	u32 reg;
	char *reason = "unknown";

	reg = readl(shdw->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, &rcfg->shdwc))
	reason = "WKUP pin";
	else if (SHDW_RTCWK(reg, &rcfg->shdwc))
	reason = "RTC";
	else if (SHDW_RTTWK(reg, &rcfg->shdwc))
	reason = "RTT";

	pr_info("AT91: Wake-Up source: %s\n", reason);
	}

	static void at91_poweroff(void)
	{
	asm volatile(
	/* Align to cache lines */
	".balign 32\n\t"

	/* Ensure AT91_SHDW_CR is in the TLB by reading it */
	" ldr r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"

	/* Power down SDRAM0 */
	" tst %0, #0\n\t"
	" beq 1f\n\t"
	" str %1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"

	/* Switch the master clock source to slow clock. */
	"1: ldr r6, [%4, %5]\n\t"
	" bic r6, r6, #" __stringify(AT91_PMC_CSS) "\n\t"
	" str r6, [%4, %5]\n\t"
	/* Wait for clock switch. */
	"2: ldr r6, [%4, #" __stringify(AT91_PMC_SR) "]\n\t"
	" tst r6, #" __stringify(AT91_PMC_MCKRDY) "\n\t"
	" beq 2b\n\t"

	/* Shutdown CPU */
	" str %3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"

	" b .\n\t"
	:
	: "r" (at91_shdwc->mpddrc_base),
	"r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
	"r" (at91_shdwc->shdwc_base),
	"r" cpu_to_le32(AT91_SHDW_KEY \| AT91_SHDW_SHDW),
	"r" (at91_shdwc->pmc_base),
	"r" (at91_shdwc->rcfg->pmc.mckr)
	: "r6");
	}

	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;
	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 %pOF\n",
	cnp);
	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_bool(cnp, "atmel,wakeup-active-high"))
	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);
	const struct reg_config *rcfg = shdw->rcfg;
	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, "debounce-delay-us", &tmp))
	mode \|= AT91_SHDW_WKUPDBC(at91_shdwc_debouncer_value(pdev, tmp));

	if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
	mode \|= SHDW_RTCWKEN(&rcfg->shdwc);

	if (of_property_read_bool(np, "atmel,wakeup-rtt-timer"))
	mode \|= SHDW_RTTWKEN(&rcfg->shdwc);

	dev_dbg(&pdev->dev, "%s: mode = %#x\n", __func__, mode);
	writel(mode, shdw->shdwc_base + AT91_SHDW_MR);

	input = at91_shdwc_get_wakeup_input(pdev, np);
	writel(input, shdw->shdwc_base + AT91_SHDW_WUIR);
	}

	static const struct reg_config sama5d2_reg_config = {
	.shdwc = {
	.wkup_pin_input = 0,
	.mr_rtcwk_shift = 17,
	.mr_rttwk_shift = SHDW_CFG_NOT_USED,
	.sr_rtcwk_shift = 5,
	.sr_rttwk_shift = SHDW_CFG_NOT_USED,
	},
	.pmc = {
	.mckr = 0x30,
	},
	.ddrc = {
	.type_offset = AT91_DDRSDRC_MDR,
	.type_mask = AT91_DDRSDRC_MD
	},
	};

	static const struct reg_config sam9x60_reg_config = {
	.shdwc = {
	.wkup_pin_input = 0,
	.mr_rtcwk_shift = 17,
	.mr_rttwk_shift = 16,
	.sr_rtcwk_shift = 5,
	.sr_rttwk_shift = 4,
	},
	.pmc = {
	.mckr = 0x28,
	},
	.ddrc = {
	.type_offset = AT91_DDRSDRC_MDR,
	.type_mask = AT91_DDRSDRC_MD
	},
	};

	static const struct reg_config sama7g5_reg_config = {
	.shdwc = {
	.wkup_pin_input = 0,
	.mr_rtcwk_shift = 17,
	.mr_rttwk_shift = 16,
	.sr_rtcwk_shift = 5,
	.sr_rttwk_shift = 4,
	},
	.pmc = {
	.mckr = 0x28,
	},
	};

	static const struct of_device_id at91_shdwc_of_match[] = {
	{
	.compatible = "atmel,sama5d2-shdwc",
	.data = &sama5d2_reg_config,
	},
	{
	.compatible = "microchip,sam9x60-shdwc",
	.data = &sam9x60_reg_config,
	},
	{
	.compatible = "microchip,sama7g5-shdwc",
	.data = &sama7g5_reg_config,
	}, {
	/sentinel/
	}
	};
	MODULE_DEVICE_TABLE(of, at91_shdwc_of_match);

	static const struct of_device_id at91_pmc_ids[] = {
	{ .compatible = "atmel,sama5d2-pmc" },
	{ .compatible = "microchip,sam9x60-pmc" },
	{ .compatible = "microchip,sama7g5-pmc" },
	{ /* Sentinel. */ }
	};

	static int __init at91_shdwc_probe(struct platform_device *pdev)
	{
	struct resource *res;
	const struct of_device_id *match;
	struct device_node *np;
	u32 ddr_type;
	int ret;

	if (!pdev->dev.of_node)
	return -ENODEV;

	if (at91_shdwc)
	return -EBUSY;

	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->shdwc_base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(at91_shdwc->shdwc_base)) {
	dev_err(&pdev->dev, "Could not map reset controller address\n");
	return PTR_ERR(at91_shdwc->shdwc_base);
	}

	match = of_match_node(at91_shdwc_of_match, pdev->dev.of_node);
	at91_shdwc->rcfg = match->data;

	at91_shdwc->sclk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(at91_shdwc->sclk))
	return PTR_ERR(at91_shdwc->sclk);

	ret = clk_prepare_enable(at91_shdwc->sclk);
	if (ret) {
	dev_err(&pdev->dev, "Could not enable slow clock\n");
	return ret;
	}

	at91_wakeup_status(pdev);

	at91_shdwc_dt_configure(pdev);

	np = of_find_matching_node(NULL, at91_pmc_ids);
	if (!np) {
	ret = -ENODEV;
	goto clk_disable;
	}

	at91_shdwc->pmc_base = of_iomap(np, 0);
	of_node_put(np);

	if (!at91_shdwc->pmc_base) {
	ret = -ENOMEM;
	goto clk_disable;
	}

	if (at91_shdwc->rcfg->ddrc.type_mask) {
	np = of_find_compatible_node(NULL, NULL,
	"atmel,sama5d3-ddramc");
	if (!np) {
	ret = -ENODEV;
	goto unmap;
	}

	at91_shdwc->mpddrc_base = of_iomap(np, 0);
	of_node_put(np);

	if (!at91_shdwc->mpddrc_base) {
	ret = -ENOMEM;
	goto unmap;
	}

	ddr_type = readl(at91_shdwc->mpddrc_base +
	at91_shdwc->rcfg->ddrc.type_offset) &
	at91_shdwc->rcfg->ddrc.type_mask;
	if (ddr_type != AT91_DDRSDRC_MD_LPDDR2 &&
	ddr_type != AT91_DDRSDRC_MD_LPDDR3) {
	iounmap(at91_shdwc->mpddrc_base);
	at91_shdwc->mpddrc_base = NULL;
	}
	}

	pm_power_off = at91_poweroff;

	return 0;

	unmap:
	iounmap(at91_shdwc->pmc_base);
	clk_disable:
	clk_disable_unprepare(at91_shdwc->sclk);

	return ret;
	}

	static int __exit at91_shdwc_remove(struct platform_device *pdev)
	{
	struct shdwc *shdw = platform_get_drvdata(pdev);

	if (pm_power_off == at91_poweroff)
	pm_power_off = NULL;

	/* Reset values to disable wake-up features */
	writel(0, shdw->shdwc_base + AT91_SHDW_MR);
	writel(0, shdw->shdwc_base + AT91_SHDW_WUIR);

	if (shdw->mpddrc_base)
	iounmap(shdw->mpddrc_base);
	iounmap(shdw->pmc_base);

	clk_disable_unprepare(shdw->sclk);

	return 0;
	}

	static struct platform_driver at91_shdwc_driver = {
	.remove = __exit_p(at91_shdwc_remove),
	.driver = {
	.name = "at91-shdwc",
	.of_match_table = at91_shdwc_of_match,
	},
	};
	module_platform_driver_probe(at91_shdwc_driver, at91_shdwc_probe);

	MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@atmel.com>");
	MODULE_DESCRIPTION("Atmel shutdown controller driver");
	MODULE_LICENSE("GPL v2");