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Commit f80cb488 authored by Nicolas Ferre's avatar Nicolas Ferre Committed by Sebastian Reichel
Browse files

power: reset: at91-shdwc: add new shutdown controller driver 



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: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: default avatarSebastian Reichel <sre@kernel.org>
parent 0e5f7d0b

MAINTAINERS

+5 −0
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@@ -1996,6 +1996,11 @@ M: Nicolas Ferre <nicolas.ferre@atmel.com> 
S:	Supported

F:	drivers/tty/serial/atmel_serial.c



ATMEL AT91 SAMA5D2-Compatible Shutdown Controller

M:	Nicolas Ferre <nicolas.ferre@atmel.com>

S:	Supported

F:	drivers/power/reset/at91-sama5d2_shdwc.c



ATMEL SAMA5D2 ADC DRIVER

M:	Ludovic Desroches <ludovic.desroches@atmel.com>

L:	linux-iio@vger.kernel.org

drivers/power/reset/Kconfig

+8 −0
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@@ -30,6 +30,14 @@ config POWER_RESET_AT91_RESET 
	  This driver supports restart for Atmel AT91SAM9 and SAMA5

	  SoCs



config POWER_RESET_AT91_SAMA5D2_SHDWC

	tristate "Atmel AT91 SAMA5D2-Compatible shutdown controller driver"

	depends on ARCH_AT91 || COMPILE_TEST

	default SOC_SAMA5

	help

	  This driver supports the alternate shutdown controller 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

drivers/power/reset/Makefile

+1 −0
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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_SAMA5D2_SHDWC) += at91-sama5d2_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

drivers/power/reset/at91-sama5d2_shdwc.c

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/*

 * 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/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		(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(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 struct clk *sclk;



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)

{

	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;

	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_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);

	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(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 const struct of_device_id at91_shdwc_of_match[] = {

	{

		.compatible = "atmel,sama5d2-shdwc",

		.data = &sama5d2_shdwc_config,

	}, {

		/*sentinel*/

	}

};

MODULE_DEVICE_TABLE(of, at91_shdwc_of_match);



static int __init at91_shdwc_probe(struct platform_device *pdev)

{

	struct resource *res;

	const struct of_device_id *match;

	int ret;



	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);

	at91_shdwc->cfg = (struct shdwc_config *)(match->data);



	sclk = devm_clk_get(&pdev->dev, NULL);

	if (IS_ERR(sclk))

		return PTR_ERR(sclk);



	ret = clk_prepare_enable(sclk);

	if (ret) {

		dev_err(&pdev->dev, "Could not enable slow clock\n");

		return ret;

	}



	at91_wakeup_status(pdev);



	at91_shdwc_dt_configure(pdev);



	pm_power_off = at91_poweroff;



	return 0;

}



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->at91_shdwc_base + AT91_SHDW_MR);

	writel(0, shdw->at91_shdwc_base + AT91_SHDW_WUIR);



	clk_disable_unprepare(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");