drivers/clk/qcom/gdsc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2015, 2017-2018, The Linux Foundation. All rights reserved.
  */

 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/export.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/ktime.h>
 #include <linux/pm_domain.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset-controller.h>
 #include <linux/slab.h>
 #include "gdsc.h"

 #define PWR_ON_MASK		BIT(31)
 #define EN_REST_WAIT_MASK	GENMASK_ULL(23, 20)
 #define EN_FEW_WAIT_MASK	GENMASK_ULL(19, 16)
 #define CLK_DIS_WAIT_MASK	GENMASK_ULL(15, 12)
 #define SW_OVERRIDE_MASK	BIT(2)
 #define HW_CONTROL_MASK		BIT(1)
 #define SW_COLLAPSE_MASK	BIT(0)
 #define GMEM_CLAMP_IO_MASK	BIT(0)
 #define GMEM_RESET_MASK		BIT(4)

 /* CFG_GDSCR */
 #define GDSC_POWER_UP_COMPLETE		BIT(16)
 #define GDSC_POWER_DOWN_COMPLETE	BIT(15)
 #define GDSC_RETAIN_FF_ENABLE		BIT(11)
 #define CFG_GDSCR_OFFSET		0x4

 /* Wait 2^n CXO cycles between all states. Here, n=2 (4 cycles). */
 #define EN_REST_WAIT_VAL	(0x2 << 20)
 #define EN_FEW_WAIT_VAL		(0x8 << 16)
 #define CLK_DIS_WAIT_VAL	(0x2 << 12)

 #define RETAIN_MEM		BIT(14)
 #define RETAIN_PERIPH		BIT(13)

 #define TIMEOUT_US		500

 #define domain_to_gdsc(domain) container_of(domain, struct gdsc, pd)

 enum gdsc_status {
 	GDSC_OFF,
 	GDSC_ON
 };

 /* Returns 1 if GDSC status is status, 0 if not, and < 0 on error */
 static int gdsc_check_status(struct gdsc *sc, enum gdsc_status status)
 {
 	unsigned int reg;
 	u32 val;
 	int ret;

 	if (sc->flags & POLL_CFG_GDSCR)
 		reg = sc->gdscr + CFG_GDSCR_OFFSET;
 	else if (sc->gds_hw_ctrl)
 		reg = sc->gds_hw_ctrl;
 	else
 		reg = sc->gdscr;

 	ret = regmap_read(sc->regmap, reg, &val);
 	if (ret)
 		return ret;

 	if (sc->flags & POLL_CFG_GDSCR) {
 		switch (status) {
 		case GDSC_ON:
 			return !!(val & GDSC_POWER_UP_COMPLETE);
 		case GDSC_OFF:
 			return !!(val & GDSC_POWER_DOWN_COMPLETE);
 		}
 	}

 	switch (status) {
 	case GDSC_ON:
 		return !!(val & PWR_ON_MASK);
 	case GDSC_OFF:
 		return !(val & PWR_ON_MASK);
 	}

 	return -EINVAL;
 }

 static int gdsc_hwctrl(struct gdsc *sc, bool en)
 {
 	u32 val = en ? HW_CONTROL_MASK : 0;

 	return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val);
 }

 static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status)
 {
 	ktime_t start;

 	start = ktime_get();
 	do {
 		if (gdsc_check_status(sc, status))
 			return 0;
 	} while (ktime_us_delta(ktime_get(), start) < TIMEOUT_US);

 	if (gdsc_check_status(sc, status))
 		return 0;

 	return -ETIMEDOUT;
 }

 static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
 {
 	int ret;
 	u32 val = (status == GDSC_ON) ? 0 : SW_COLLAPSE_MASK;

 	if (status == GDSC_ON && sc->rsupply) {
 		ret = regulator_enable(sc->rsupply);
 		if (ret < 0)
 			return ret;
 	}

 	ret = regmap_update_bits(sc->regmap, sc->gdscr, SW_COLLAPSE_MASK, val);
 	if (ret)
 		return ret;

 	/* If disabling votable gdscs, don't poll on status */
 	if ((sc->flags & VOTABLE) && status == GDSC_OFF) {
 		/*
 		 * Add a short delay here to ensure that an enable
 		 * right after it was disabled does not put it in an
 		 * unknown state
 		 */
 		udelay(TIMEOUT_US);
 		return 0;
 	}

 	if (sc->gds_hw_ctrl) {
 		/*
 		 * The gds hw controller asserts/de-asserts the status bit soon
 		 * after it receives a power on/off request from a master.
 		 * The controller then takes around 8 xo cycles to start its
 		 * internal state machine and update the status bit. During
 		 * this time, the status bit does not reflect the true status
 		 * of the core.
 		 * Add a delay of 1 us between writing to the SW_COLLAPSE bit
 		 * and polling the status bit.
 		 */
 		udelay(1);
 	}

 	ret = gdsc_poll_status(sc, status);
 	WARN(ret, "%s status stuck at 'o%s'", sc->pd.name, status ? "ff" : "n");

 	if (!ret && status == GDSC_OFF && sc->rsupply) {
 		ret = regulator_disable(sc->rsupply);
 		if (ret < 0)
 			return ret;
 	}

 	return ret;
 }

 static inline int gdsc_deassert_reset(struct gdsc *sc)
 {
 	int i;

 	for (i = 0; i < sc->reset_count; i++)
 		sc->rcdev->ops->deassert(sc->rcdev, sc->resets[i]);
 	return 0;
 }

 static inline int gdsc_assert_reset(struct gdsc *sc)
 {
 	int i;

 	for (i = 0; i < sc->reset_count; i++)
 		sc->rcdev->ops->assert(sc->rcdev, sc->resets[i]);
 	return 0;
 }

 static inline void gdsc_force_mem_on(struct gdsc *sc)
 {
 	int i;
 	u32 mask = RETAIN_MEM | RETAIN_PERIPH;

 	for (i = 0; i < sc->cxc_count; i++)
 		regmap_update_bits(sc->regmap, sc->cxcs[i], mask, mask);
 }

 static inline void gdsc_clear_mem_on(struct gdsc *sc)
 {
 	int i;
 	u32 mask = RETAIN_MEM | RETAIN_PERIPH;

 	for (i = 0; i < sc->cxc_count; i++)
 		regmap_update_bits(sc->regmap, sc->cxcs[i], mask, 0);
 }

 static inline void gdsc_deassert_clamp_io(struct gdsc *sc)
 {
 	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
 			   GMEM_CLAMP_IO_MASK, 0);
 }

 static inline void gdsc_assert_clamp_io(struct gdsc *sc)
 {
 	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
 			   GMEM_CLAMP_IO_MASK, 1);
 }

 static inline void gdsc_assert_reset_aon(struct gdsc *sc)
 {
 	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
 			   GMEM_RESET_MASK, 1);
 	udelay(1);
 	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
 			   GMEM_RESET_MASK, 0);
 }

 static void gdsc_retain_ff_on(struct gdsc *sc)
 {
 	u32 mask = GDSC_RETAIN_FF_ENABLE;

 	regmap_update_bits(sc->regmap, sc->gdscr, mask, mask);
 }

 static int gdsc_enable(struct generic_pm_domain *domain)
 {
 	struct gdsc *sc = domain_to_gdsc(domain);
 	int ret;

 	if (sc->pwrsts == PWRSTS_ON)
 		return gdsc_deassert_reset(sc);

 	if (sc->flags & SW_RESET) {
 		gdsc_assert_reset(sc);
 		udelay(1);
 		gdsc_deassert_reset(sc);
 	}

 	if (sc->flags & CLAMP_IO) {
 		if (sc->flags & AON_RESET)
 			gdsc_assert_reset_aon(sc);
 		gdsc_deassert_clamp_io(sc);
 	}

 	ret = gdsc_toggle_logic(sc, GDSC_ON);
 	if (ret)
 		return ret;

 	if (sc->pwrsts & PWRSTS_OFF)
 		gdsc_force_mem_on(sc);

 	/*
 	 * If clocks to this power domain were already on, they will take an
 	 * additional 4 clock cycles to re-enable after the power domain is
 	 * enabled. Delay to account for this. A delay is also needed to ensure
 	 * clocks are not enabled within 400ns of enabling power to the
 	 * memories.
 	 */
 	udelay(1);

 	/* Turn on HW trigger mode if supported */
 	if (sc->flags & HW_CTRL) {
 		ret = gdsc_hwctrl(sc, true);
 		if (ret)
 			return ret;
 		/*
 		 * Wait for the GDSC to go through a power down and
 		 * up cycle.  In case a firmware ends up polling status
 		 * bits for the gdsc, it might read an 'on' status before
 		 * the GDSC can finish the power cycle.
 		 * We wait 1us before returning to ensure the firmware
 		 * can't immediately poll the status bits.
 		 */
 		udelay(1);
 	}

 	if (sc->flags & RETAIN_FF_ENABLE)
 		gdsc_retain_ff_on(sc);

 	return 0;
 }

 static int gdsc_disable(struct generic_pm_domain *domain)
 {
 	struct gdsc *sc = domain_to_gdsc(domain);
 	int ret;

 	if (sc->pwrsts == PWRSTS_ON)
 		return gdsc_assert_reset(sc);

 	/* Turn off HW trigger mode if supported */
 	if (sc->flags & HW_CTRL) {
 		ret = gdsc_hwctrl(sc, false);
 		if (ret < 0)
 			return ret;
 		/*
 		 * Wait for the GDSC to go through a power down and
 		 * up cycle.  In case we end up polling status
 		 * bits for the gdsc before the power cycle is completed
 		 * it might read an 'on' status wrongly.
 		 */
 		udelay(1);

 		ret = gdsc_poll_status(sc, GDSC_ON);
 		if (ret)
 			return ret;
 	}

 	if (sc->pwrsts & PWRSTS_OFF)
 		gdsc_clear_mem_on(sc);

 	ret = gdsc_toggle_logic(sc, GDSC_OFF);
 	if (ret)
 		return ret;

 	if (sc->flags & CLAMP_IO)
 		gdsc_assert_clamp_io(sc);

 	return 0;
 }

 static int gdsc_init(struct gdsc *sc)
 {
 	u32 mask, val;
 	int on, ret;

 	/*
 	 * Disable HW trigger: collapse/restore occur based on registers writes.
 	 * Disable SW override: Use hardware state-machine for sequencing.
 	 * Configure wait time between states.
 	 */
 	mask = HW_CONTROL_MASK | SW_OVERRIDE_MASK |
 	       EN_REST_WAIT_MASK | EN_FEW_WAIT_MASK | CLK_DIS_WAIT_MASK;
 	val = EN_REST_WAIT_VAL | EN_FEW_WAIT_VAL | CLK_DIS_WAIT_VAL;
 	ret = regmap_update_bits(sc->regmap, sc->gdscr, mask, val);
 	if (ret)
 		return ret;

 	/* Force gdsc ON if only ON state is supported */
 	if (sc->pwrsts == PWRSTS_ON) {
 		ret = gdsc_toggle_logic(sc, GDSC_ON);
 		if (ret)
 			return ret;
 	}

 	on = gdsc_check_status(sc, GDSC_ON);
 	if (on < 0)
 		return on;

 	/*
 	 * Votable GDSCs can be ON due to Vote from other masters.
 	 * If a Votable GDSC is ON, make sure we have a Vote.
 	 */
 	if ((sc->flags & VOTABLE) && on)
 		gdsc_enable(&sc->pd);

 	/*
 	 * Make sure the retain bit is set if the GDSC is already on, otherwise
 	 * we end up turning off the GDSC and destroying all the register
 	 * contents that we thought we were saving.
 	 */
 	if ((sc->flags & RETAIN_FF_ENABLE) && on)
 		gdsc_retain_ff_on(sc);

 	/* If ALWAYS_ON GDSCs are not ON, turn them ON */
 	if (sc->flags & ALWAYS_ON) {
 		if (!on)
 			gdsc_enable(&sc->pd);
 		on = true;
 		sc->pd.flags |= GENPD_FLAG_ALWAYS_ON;
 	}

 	if (on || (sc->pwrsts & PWRSTS_RET))
 		gdsc_force_mem_on(sc);
 	else
 		gdsc_clear_mem_on(sc);

 	if (!sc->pd.power_off)
 		sc->pd.power_off = gdsc_disable;
 	if (!sc->pd.power_on)
 		sc->pd.power_on = gdsc_enable;
 	pm_genpd_init(&sc->pd, NULL, !on);

 	return 0;
 }

 int gdsc_register(struct gdsc_desc *desc,
 		  struct reset_controller_dev *rcdev, struct regmap *regmap)
 {
 	int i, ret;
 	struct genpd_onecell_data *data;
 	struct device *dev = desc->dev;
 	struct gdsc **scs = desc->scs;
 	size_t num = desc->num;

 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->domains = devm_kcalloc(dev, num, sizeof(*data->domains),
 				     GFP_KERNEL);
 	if (!data->domains)
 		return -ENOMEM;

 	for (i = 0; i < num; i++) {
 		if (!scs[i] || !scs[i]->supply)
 			continue;

 		scs[i]->rsupply = devm_regulator_get(dev, scs[i]->supply);
 		if (IS_ERR(scs[i]->rsupply))
 			return PTR_ERR(scs[i]->rsupply);
 	}

 	data->num_domains = num;
 	for (i = 0; i < num; i++) {
 		if (!scs[i])
 			continue;
 		scs[i]->regmap = regmap;
 		scs[i]->rcdev = rcdev;
 		ret = gdsc_init(scs[i]);
 		if (ret)
 			return ret;
 		data->domains[i] = &scs[i]->pd;
 	}

 	/* Add subdomains */
 	for (i = 0; i < num; i++) {
 		if (!scs[i])
 			continue;
 		if (scs[i]->parent)
 			pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
 	}

 	return of_genpd_add_provider_onecell(dev->of_node, data);
 }

 void gdsc_unregister(struct gdsc_desc *desc)
 {
 	int i;
 	struct device *dev = desc->dev;
 	struct gdsc **scs = desc->scs;
 	size_t num = desc->num;

 	/* Remove subdomains */
 	for (i = 0; i < num; i++) {
 		if (!scs[i])
 			continue;
 		if (scs[i]->parent)
 			pm_genpd_remove_subdomain(scs[i]->parent, &scs[i]->pd);
 	}
 	of_genpd_del_provider(dev->of_node);
 }

 /*
  * On SDM845+ the GPU GX domain is *almost* entirely controlled by the GMU
  * running in the CX domain so the CPU doesn't need to know anything about the
  * GX domain EXCEPT....
  *
  * Hardware constraints dictate that the GX be powered down before the CX. If
  * the GMU crashes it could leave the GX on. In order to successfully bring back
  * the device the CPU needs to disable the GX headswitch. There being no sane
  * way to reach in and touch that register from deep inside the GPU driver we
  * need to set up the infrastructure to be able to ensure that the GPU can
  * ensure that the GX is off during this super special case. We do this by
  * defining a GX gdsc with a dummy enable function and a "default" disable
  * function.
  *
  * This allows us to attach with genpd_dev_pm_attach_by_name() in the GPU
  * driver. During power up, nothing will happen from the CPU (and the GMU will
  * power up normally but during power down this will ensure that the GX domain
  * is *really* off - this gives us a semi standard way of doing what we need.
  */
 int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain)
 {
 	/* Do nothing but give genpd the impression that we were successful */
 	return 0;
 }
 EXPORT_SYMBOL_GPL(gdsc_gx_do_nothing_enable);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (c) 2015, 2017-2018, The Linux Foundation. All rights reserved.
	*/

	#include <linux/bitops.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/export.h>
	#include <linux/jiffies.h>
	#include <linux/kernel.h>
	#include <linux/ktime.h>
	#include <linux/pm_domain.h>
	#include <linux/regmap.h>
	#include <linux/regulator/consumer.h>
	#include <linux/reset-controller.h>
	#include <linux/slab.h>
	#include "gdsc.h"

	#define PWR_ON_MASK BIT(31)
	#define EN_REST_WAIT_MASK GENMASK_ULL(23, 20)
	#define EN_FEW_WAIT_MASK GENMASK_ULL(19, 16)
	#define CLK_DIS_WAIT_MASK GENMASK_ULL(15, 12)
	#define SW_OVERRIDE_MASK BIT(2)
	#define HW_CONTROL_MASK BIT(1)
	#define SW_COLLAPSE_MASK BIT(0)
	#define GMEM_CLAMP_IO_MASK BIT(0)
	#define GMEM_RESET_MASK BIT(4)

	/* CFG_GDSCR */
	#define GDSC_POWER_UP_COMPLETE BIT(16)
	#define GDSC_POWER_DOWN_COMPLETE BIT(15)
	#define GDSC_RETAIN_FF_ENABLE BIT(11)
	#define CFG_GDSCR_OFFSET 0x4

	/* Wait 2^n CXO cycles between all states. Here, n=2 (4 cycles). */
	#define EN_REST_WAIT_VAL (0x2 << 20)
	#define EN_FEW_WAIT_VAL (0x8 << 16)
	#define CLK_DIS_WAIT_VAL (0x2 << 12)

	#define RETAIN_MEM BIT(14)
	#define RETAIN_PERIPH BIT(13)

	#define TIMEOUT_US 500

	#define domain_to_gdsc(domain) container_of(domain, struct gdsc, pd)

	enum gdsc_status {
	GDSC_OFF,
	GDSC_ON
	};

	/* Returns 1 if GDSC status is status, 0 if not, and < 0 on error */
	static int gdsc_check_status(struct gdsc *sc, enum gdsc_status status)
	{
	unsigned int reg;
	u32 val;
	int ret;

	if (sc->flags & POLL_CFG_GDSCR)
	reg = sc->gdscr + CFG_GDSCR_OFFSET;
	else if (sc->gds_hw_ctrl)
	reg = sc->gds_hw_ctrl;
	else
	reg = sc->gdscr;

	ret = regmap_read(sc->regmap, reg, &val);
	if (ret)
	return ret;

	if (sc->flags & POLL_CFG_GDSCR) {
	switch (status) {
	case GDSC_ON:
	return !!(val & GDSC_POWER_UP_COMPLETE);
	case GDSC_OFF:
	return !!(val & GDSC_POWER_DOWN_COMPLETE);
	}
	}

	switch (status) {
	case GDSC_ON:
	return !!(val & PWR_ON_MASK);
	case GDSC_OFF:
	return !(val & PWR_ON_MASK);
	}

	return -EINVAL;
	}

	static int gdsc_hwctrl(struct gdsc *sc, bool en)
	{
	u32 val = en ? HW_CONTROL_MASK : 0;

	return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val);
	}

	static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status)
	{
	ktime_t start;

	start = ktime_get();
	do {
	if (gdsc_check_status(sc, status))
	return 0;
	} while (ktime_us_delta(ktime_get(), start) < TIMEOUT_US);

	if (gdsc_check_status(sc, status))
	return 0;

	return -ETIMEDOUT;
	}

	static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
	{
	int ret;
	u32 val = (status == GDSC_ON) ? 0 : SW_COLLAPSE_MASK;

	if (status == GDSC_ON && sc->rsupply) {
	ret = regulator_enable(sc->rsupply);
	if (ret < 0)
	return ret;
	}

	ret = regmap_update_bits(sc->regmap, sc->gdscr, SW_COLLAPSE_MASK, val);
	if (ret)
	return ret;

	/* If disabling votable gdscs, don't poll on status */
	if ((sc->flags & VOTABLE) && status == GDSC_OFF) {
	/*
	* Add a short delay here to ensure that an enable
	* right after it was disabled does not put it in an
	* unknown state
	*/
	udelay(TIMEOUT_US);
	return 0;
	}

	if (sc->gds_hw_ctrl) {
	/*
	* The gds hw controller asserts/de-asserts the status bit soon
	* after it receives a power on/off request from a master.
	* The controller then takes around 8 xo cycles to start its
	* internal state machine and update the status bit. During
	* this time, the status bit does not reflect the true status
	* of the core.
	* Add a delay of 1 us between writing to the SW_COLLAPSE bit
	* and polling the status bit.
	*/
	udelay(1);
	}

	ret = gdsc_poll_status(sc, status);
	WARN(ret, "%s status stuck at 'o%s'", sc->pd.name, status ? "ff" : "n");

	if (!ret && status == GDSC_OFF && sc->rsupply) {
	ret = regulator_disable(sc->rsupply);
	if (ret < 0)
	return ret;
	}

	return ret;
	}

	static inline int gdsc_deassert_reset(struct gdsc *sc)
	{
	int i;

	for (i = 0; i < sc->reset_count; i++)
	sc->rcdev->ops->deassert(sc->rcdev, sc->resets[i]);
	return 0;
	}

	static inline int gdsc_assert_reset(struct gdsc *sc)
	{
	int i;

	for (i = 0; i < sc->reset_count; i++)
	sc->rcdev->ops->assert(sc->rcdev, sc->resets[i]);
	return 0;
	}

	static inline void gdsc_force_mem_on(struct gdsc *sc)
	{
	int i;
	u32 mask = RETAIN_MEM \| RETAIN_PERIPH;

	for (i = 0; i < sc->cxc_count; i++)
	regmap_update_bits(sc->regmap, sc->cxcs[i], mask, mask);
	}

	static inline void gdsc_clear_mem_on(struct gdsc *sc)
	{
	int i;
	u32 mask = RETAIN_MEM \| RETAIN_PERIPH;

	for (i = 0; i < sc->cxc_count; i++)
	regmap_update_bits(sc->regmap, sc->cxcs[i], mask, 0);
	}

	static inline void gdsc_deassert_clamp_io(struct gdsc *sc)
	{
	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
	GMEM_CLAMP_IO_MASK, 0);
	}

	static inline void gdsc_assert_clamp_io(struct gdsc *sc)
	{
	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
	GMEM_CLAMP_IO_MASK, 1);
	}

	static inline void gdsc_assert_reset_aon(struct gdsc *sc)
	{
	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
	GMEM_RESET_MASK, 1);
	udelay(1);
	regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
	GMEM_RESET_MASK, 0);
	}

	static void gdsc_retain_ff_on(struct gdsc *sc)
	{
	u32 mask = GDSC_RETAIN_FF_ENABLE;

	regmap_update_bits(sc->regmap, sc->gdscr, mask, mask);
	}

	static int gdsc_enable(struct generic_pm_domain *domain)
	{
	struct gdsc *sc = domain_to_gdsc(domain);
	int ret;

	if (sc->pwrsts == PWRSTS_ON)
	return gdsc_deassert_reset(sc);

	if (sc->flags & SW_RESET) {
	gdsc_assert_reset(sc);
	udelay(1);
	gdsc_deassert_reset(sc);
	}

	if (sc->flags & CLAMP_IO) {
	if (sc->flags & AON_RESET)
	gdsc_assert_reset_aon(sc);
	gdsc_deassert_clamp_io(sc);
	}

	ret = gdsc_toggle_logic(sc, GDSC_ON);
	if (ret)
	return ret;

	if (sc->pwrsts & PWRSTS_OFF)
	gdsc_force_mem_on(sc);

	/*
	* If clocks to this power domain were already on, they will take an
	* additional 4 clock cycles to re-enable after the power domain is
	* enabled. Delay to account for this. A delay is also needed to ensure
	* clocks are not enabled within 400ns of enabling power to the
	* memories.
	*/
	udelay(1);

	/* Turn on HW trigger mode if supported */
	if (sc->flags & HW_CTRL) {
	ret = gdsc_hwctrl(sc, true);
	if (ret)
	return ret;
	/*
	* Wait for the GDSC to go through a power down and
	* up cycle. In case a firmware ends up polling status
	* bits for the gdsc, it might read an 'on' status before
	* the GDSC can finish the power cycle.
	* We wait 1us before returning to ensure the firmware
	* can't immediately poll the status bits.
	*/
	udelay(1);
	}

	if (sc->flags & RETAIN_FF_ENABLE)
	gdsc_retain_ff_on(sc);

	return 0;
	}

	static int gdsc_disable(struct generic_pm_domain *domain)
	{
	struct gdsc *sc = domain_to_gdsc(domain);
	int ret;

	if (sc->pwrsts == PWRSTS_ON)
	return gdsc_assert_reset(sc);

	/* Turn off HW trigger mode if supported */
	if (sc->flags & HW_CTRL) {
	ret = gdsc_hwctrl(sc, false);
	if (ret < 0)
	return ret;
	/*
	* Wait for the GDSC to go through a power down and
	* up cycle. In case we end up polling status
	* bits for the gdsc before the power cycle is completed
	* it might read an 'on' status wrongly.
	*/
	udelay(1);

	ret = gdsc_poll_status(sc, GDSC_ON);
	if (ret)
	return ret;
	}

	if (sc->pwrsts & PWRSTS_OFF)
	gdsc_clear_mem_on(sc);

	ret = gdsc_toggle_logic(sc, GDSC_OFF);
	if (ret)
	return ret;

	if (sc->flags & CLAMP_IO)
	gdsc_assert_clamp_io(sc);

	return 0;
	}

	static int gdsc_init(struct gdsc *sc)
	{
	u32 mask, val;
	int on, ret;

	/*
	* Disable HW trigger: collapse/restore occur based on registers writes.
	* Disable SW override: Use hardware state-machine for sequencing.
	* Configure wait time between states.
	*/
	mask = HW_CONTROL_MASK \| SW_OVERRIDE_MASK \|
	EN_REST_WAIT_MASK \| EN_FEW_WAIT_MASK \| CLK_DIS_WAIT_MASK;
	val = EN_REST_WAIT_VAL \| EN_FEW_WAIT_VAL \| CLK_DIS_WAIT_VAL;
	ret = regmap_update_bits(sc->regmap, sc->gdscr, mask, val);
	if (ret)
	return ret;

	/* Force gdsc ON if only ON state is supported */
	if (sc->pwrsts == PWRSTS_ON) {
	ret = gdsc_toggle_logic(sc, GDSC_ON);
	if (ret)
	return ret;
	}

	on = gdsc_check_status(sc, GDSC_ON);
	if (on < 0)
	return on;

	/*
	* Votable GDSCs can be ON due to Vote from other masters.
	* If a Votable GDSC is ON, make sure we have a Vote.
	*/
	if ((sc->flags & VOTABLE) && on)
	gdsc_enable(&sc->pd);

	/*
	* Make sure the retain bit is set if the GDSC is already on, otherwise
	* we end up turning off the GDSC and destroying all the register
	* contents that we thought we were saving.
	*/
	if ((sc->flags & RETAIN_FF_ENABLE) && on)
	gdsc_retain_ff_on(sc);

	/* If ALWAYS_ON GDSCs are not ON, turn them ON */
	if (sc->flags & ALWAYS_ON) {
	if (!on)
	gdsc_enable(&sc->pd);
	on = true;
	sc->pd.flags \|= GENPD_FLAG_ALWAYS_ON;
	}

	if (on \|\| (sc->pwrsts & PWRSTS_RET))
	gdsc_force_mem_on(sc);
	else
	gdsc_clear_mem_on(sc);

	if (!sc->pd.power_off)
	sc->pd.power_off = gdsc_disable;
	if (!sc->pd.power_on)
	sc->pd.power_on = gdsc_enable;
	pm_genpd_init(&sc->pd, NULL, !on);

	return 0;
	}

	int gdsc_register(struct gdsc_desc *desc,
	struct reset_controller_dev rcdev, struct regmap regmap)
	{
	int i, ret;
	struct genpd_onecell_data *data;
	struct device *dev = desc->dev;
	struct gdsc **scs = desc->scs;
	size_t num = desc->num;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->domains = devm_kcalloc(dev, num, sizeof(*data->domains),
	GFP_KERNEL);
	if (!data->domains)
	return -ENOMEM;

	for (i = 0; i < num; i++) {
	if (!scs[i] \|\| !scs[i]->supply)
	continue;

	scs[i]->rsupply = devm_regulator_get(dev, scs[i]->supply);
	if (IS_ERR(scs[i]->rsupply))
	return PTR_ERR(scs[i]->rsupply);
	}

	data->num_domains = num;
	for (i = 0; i < num; i++) {
	if (!scs[i])
	continue;
	scs[i]->regmap = regmap;
	scs[i]->rcdev = rcdev;
	ret = gdsc_init(scs[i]);
	if (ret)
	return ret;
	data->domains[i] = &scs[i]->pd;
	}

	/* Add subdomains */
	for (i = 0; i < num; i++) {
	if (!scs[i])
	continue;
	if (scs[i]->parent)
	pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
	}

	return of_genpd_add_provider_onecell(dev->of_node, data);
	}

	void gdsc_unregister(struct gdsc_desc *desc)
	{
	int i;
	struct device *dev = desc->dev;
	struct gdsc **scs = desc->scs;
	size_t num = desc->num;

	/* Remove subdomains */
	for (i = 0; i < num; i++) {
	if (!scs[i])
	continue;
	if (scs[i]->parent)
	pm_genpd_remove_subdomain(scs[i]->parent, &scs[i]->pd);
	}
	of_genpd_del_provider(dev->of_node);
	}

	/*
	* On SDM845+ the GPU GX domain is almost entirely controlled by the GMU
	* running in the CX domain so the CPU doesn't need to know anything about the
	* GX domain EXCEPT....
	*
	* Hardware constraints dictate that the GX be powered down before the CX. If
	* the GMU crashes it could leave the GX on. In order to successfully bring back
	* the device the CPU needs to disable the GX headswitch. There being no sane
	* way to reach in and touch that register from deep inside the GPU driver we
	* need to set up the infrastructure to be able to ensure that the GPU can
	* ensure that the GX is off during this super special case. We do this by
	* defining a GX gdsc with a dummy enable function and a "default" disable
	* function.
	*
	* This allows us to attach with genpd_dev_pm_attach_by_name() in the GPU
	* driver. During power up, nothing will happen from the CPU (and the GMU will
	* power up normally but during power down this will ensure that the GX domain
	* is really off - this gives us a semi standard way of doing what we need.
	*/
	int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain)
	{
	/* Do nothing but give genpd the impression that we were successful */
	return 0;
	}
	EXPORT_SYMBOL_GPL(gdsc_gx_do_nothing_enable);