drivers/pwm/pwm-tiehrpwm.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * EHRPWM PWM driver
  *
  * Copyright (C) 2012 Texas Instruments, Inc. - https://www.ti.com/
  */

 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/io.h>
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/pm_runtime.h>
 #include <linux/of_device.h>

 /* EHRPWM registers and bits definitions */

 /* Time base module registers */
 #define TBCTL			0x00
 #define TBPRD			0x0A

 #define TBCTL_PRDLD_MASK	BIT(3)
 #define TBCTL_PRDLD_SHDW	0
 #define TBCTL_PRDLD_IMDT	BIT(3)
 #define TBCTL_CLKDIV_MASK	(BIT(12) | BIT(11) | BIT(10) | BIT(9) | \
 				BIT(8) | BIT(7))
 #define TBCTL_CTRMODE_MASK	(BIT(1) | BIT(0))
 #define TBCTL_CTRMODE_UP	0
 #define TBCTL_CTRMODE_DOWN	BIT(0)
 #define TBCTL_CTRMODE_UPDOWN	BIT(1)
 #define TBCTL_CTRMODE_FREEZE	(BIT(1) | BIT(0))

 #define TBCTL_HSPCLKDIV_SHIFT	7
 #define TBCTL_CLKDIV_SHIFT	10

 #define CLKDIV_MAX		7
 #define HSPCLKDIV_MAX		7
 #define PERIOD_MAX		0xFFFF

 /* compare module registers */
 #define CMPA			0x12
 #define CMPB			0x14

 /* Action qualifier module registers */
 #define AQCTLA			0x16
 #define AQCTLB			0x18
 #define AQSFRC			0x1A
 #define AQCSFRC			0x1C

 #define AQCTL_CBU_MASK		(BIT(9) | BIT(8))
 #define AQCTL_CBU_FRCLOW	BIT(8)
 #define AQCTL_CBU_FRCHIGH	BIT(9)
 #define AQCTL_CBU_FRCTOGGLE	(BIT(9) | BIT(8))
 #define AQCTL_CAU_MASK		(BIT(5) | BIT(4))
 #define AQCTL_CAU_FRCLOW	BIT(4)
 #define AQCTL_CAU_FRCHIGH	BIT(5)
 #define AQCTL_CAU_FRCTOGGLE	(BIT(5) | BIT(4))
 #define AQCTL_PRD_MASK		(BIT(3) | BIT(2))
 #define AQCTL_PRD_FRCLOW	BIT(2)
 #define AQCTL_PRD_FRCHIGH	BIT(3)
 #define AQCTL_PRD_FRCTOGGLE	(BIT(3) | BIT(2))
 #define AQCTL_ZRO_MASK		(BIT(1) | BIT(0))
 #define AQCTL_ZRO_FRCLOW	BIT(0)
 #define AQCTL_ZRO_FRCHIGH	BIT(1)
 #define AQCTL_ZRO_FRCTOGGLE	(BIT(1) | BIT(0))

 #define AQCTL_CHANA_POLNORMAL	(AQCTL_CAU_FRCLOW | AQCTL_PRD_FRCHIGH | \
 				AQCTL_ZRO_FRCHIGH)
 #define AQCTL_CHANA_POLINVERSED	(AQCTL_CAU_FRCHIGH | AQCTL_PRD_FRCLOW | \
 				AQCTL_ZRO_FRCLOW)
 #define AQCTL_CHANB_POLNORMAL	(AQCTL_CBU_FRCLOW | AQCTL_PRD_FRCHIGH | \
 				AQCTL_ZRO_FRCHIGH)
 #define AQCTL_CHANB_POLINVERSED	(AQCTL_CBU_FRCHIGH | AQCTL_PRD_FRCLOW | \
 				AQCTL_ZRO_FRCLOW)

 #define AQSFRC_RLDCSF_MASK	(BIT(7) | BIT(6))
 #define AQSFRC_RLDCSF_ZRO	0
 #define AQSFRC_RLDCSF_PRD	BIT(6)
 #define AQSFRC_RLDCSF_ZROPRD	BIT(7)
 #define AQSFRC_RLDCSF_IMDT	(BIT(7) | BIT(6))

 #define AQCSFRC_CSFB_MASK	(BIT(3) | BIT(2))
 #define AQCSFRC_CSFB_FRCDIS	0
 #define AQCSFRC_CSFB_FRCLOW	BIT(2)
 #define AQCSFRC_CSFB_FRCHIGH	BIT(3)
 #define AQCSFRC_CSFB_DISSWFRC	(BIT(3) | BIT(2))
 #define AQCSFRC_CSFA_MASK	(BIT(1) | BIT(0))
 #define AQCSFRC_CSFA_FRCDIS	0
 #define AQCSFRC_CSFA_FRCLOW	BIT(0)
 #define AQCSFRC_CSFA_FRCHIGH	BIT(1)
 #define AQCSFRC_CSFA_DISSWFRC	(BIT(1) | BIT(0))

 #define NUM_PWM_CHANNEL		2	/* EHRPWM channels */

 struct ehrpwm_context {
 	u16 tbctl;
 	u16 tbprd;
 	u16 cmpa;
 	u16 cmpb;
 	u16 aqctla;
 	u16 aqctlb;
 	u16 aqsfrc;
 	u16 aqcsfrc;
 };

 struct ehrpwm_pwm_chip {
 	struct pwm_chip chip;
 	unsigned long clk_rate;
 	void __iomem *mmio_base;
 	unsigned long period_cycles[NUM_PWM_CHANNEL];
 	enum pwm_polarity polarity[NUM_PWM_CHANNEL];
 	struct clk *tbclk;
 	struct ehrpwm_context ctx;
 };

 static inline struct ehrpwm_pwm_chip *to_ehrpwm_pwm_chip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct ehrpwm_pwm_chip, chip);
 }

 static inline u16 ehrpwm_read(void __iomem *base, unsigned int offset)
 {
 	return readw(base + offset);
 }

 static inline void ehrpwm_write(void __iomem *base, unsigned int offset,
 				u16 value)
 {
 	writew(value, base + offset);
 }

 static void ehrpwm_modify(void __iomem *base, unsigned int offset, u16 mask,
 			  u16 value)
 {
 	unsigned short val;

 	val = readw(base + offset);
 	val &= ~mask;
 	val |= value & mask;
 	writew(val, base + offset);
 }

 /**
  * set_prescale_div -	Set up the prescaler divider function
  * @rqst_prescaler:	prescaler value min
  * @prescale_div:	prescaler value set
  * @tb_clk_div:		Time Base Control prescaler bits
  */
 static int set_prescale_div(unsigned long rqst_prescaler, u16 *prescale_div,
 			    u16 *tb_clk_div)
 {
 	unsigned int clkdiv, hspclkdiv;

 	for (clkdiv = 0; clkdiv <= CLKDIV_MAX; clkdiv++) {
 		for (hspclkdiv = 0; hspclkdiv <= HSPCLKDIV_MAX; hspclkdiv++) {
 			/*
 			 * calculations for prescaler value :
 			 * prescale_div = HSPCLKDIVIDER * CLKDIVIDER.
 			 * HSPCLKDIVIDER =  2 ** hspclkdiv
 			 * CLKDIVIDER = (1),		if clkdiv == 0 *OR*
 			 *		(2 * clkdiv),	if clkdiv != 0
 			 *
 			 * Configure prescale_div value such that period
 			 * register value is less than 65535.
 			 */

 			*prescale_div = (1 << clkdiv) *
 					(hspclkdiv ? (hspclkdiv * 2) : 1);
 			if (*prescale_div > rqst_prescaler) {
 				*tb_clk_div = (clkdiv << TBCTL_CLKDIV_SHIFT) |
 					(hspclkdiv << TBCTL_HSPCLKDIV_SHIFT);
 				return 0;
 			}
 		}
 	}

 	return 1;
 }

 static void configure_polarity(struct ehrpwm_pwm_chip *pc, int chan)
 {
 	u16 aqctl_val, aqctl_mask;
 	unsigned int aqctl_reg;

 	/*
 	 * Configure PWM output to HIGH/LOW level on counter
 	 * reaches compare register value and LOW/HIGH level
 	 * on counter value reaches period register value and
 	 * zero value on counter
 	 */
 	if (chan == 1) {
 		aqctl_reg = AQCTLB;
 		aqctl_mask = AQCTL_CBU_MASK;

 		if (pc->polarity[chan] == PWM_POLARITY_INVERSED)
 			aqctl_val = AQCTL_CHANB_POLINVERSED;
 		else
 			aqctl_val = AQCTL_CHANB_POLNORMAL;
 	} else {
 		aqctl_reg = AQCTLA;
 		aqctl_mask = AQCTL_CAU_MASK;

 		if (pc->polarity[chan] == PWM_POLARITY_INVERSED)
 			aqctl_val = AQCTL_CHANA_POLINVERSED;
 		else
 			aqctl_val = AQCTL_CHANA_POLNORMAL;
 	}

 	aqctl_mask |= AQCTL_PRD_MASK | AQCTL_ZRO_MASK;
 	ehrpwm_modify(pc->mmio_base, aqctl_reg, aqctl_mask, aqctl_val);
 }

 /*
  * period_ns = 10^9 * (ps_divval * period_cycles) / PWM_CLK_RATE
  * duty_ns   = 10^9 * (ps_divval * duty_cycles) / PWM_CLK_RATE
  */
 static int ehrpwm_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			     u64 duty_ns, u64 period_ns)
 {
 	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
 	u32 period_cycles, duty_cycles;
 	u16 ps_divval, tb_divval;
 	unsigned int i, cmp_reg;
 	unsigned long long c;

 	if (period_ns > NSEC_PER_SEC)
 		return -ERANGE;

 	c = pc->clk_rate;
 	c = c * period_ns;
 	do_div(c, NSEC_PER_SEC);
 	period_cycles = (unsigned long)c;

 	if (period_cycles < 1) {
 		period_cycles = 1;
 		duty_cycles = 1;
 	} else {
 		c = pc->clk_rate;
 		c = c * duty_ns;
 		do_div(c, NSEC_PER_SEC);
 		duty_cycles = (unsigned long)c;
 	}

 	/*
 	 * Period values should be same for multiple PWM channels as IP uses
 	 * same period register for multiple channels.
 	 */
 	for (i = 0; i < NUM_PWM_CHANNEL; i++) {
 		if (pc->period_cycles[i] &&
 				(pc->period_cycles[i] != period_cycles)) {
 			/*
 			 * Allow channel to reconfigure period if no other
 			 * channels being configured.
 			 */
 			if (i == pwm->hwpwm)
 				continue;

 			dev_err(chip->dev,
 				"period value conflicts with channel %u\n",
 				i);
 			return -EINVAL;
 		}
 	}

 	pc->period_cycles[pwm->hwpwm] = period_cycles;

 	/* Configure clock prescaler to support Low frequency PWM wave */
 	if (set_prescale_div(period_cycles/PERIOD_MAX, &ps_divval,
 			     &tb_divval)) {
 		dev_err(chip->dev, "Unsupported values\n");
 		return -EINVAL;
 	}

 	pm_runtime_get_sync(chip->dev);

 	/* Update clock prescaler values */
 	ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CLKDIV_MASK, tb_divval);

 	/* Update period & duty cycle with presacler division */
 	period_cycles = period_cycles / ps_divval;
 	duty_cycles = duty_cycles / ps_divval;

 	/* Configure shadow loading on Period register */
 	ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_PRDLD_MASK, TBCTL_PRDLD_SHDW);

 	ehrpwm_write(pc->mmio_base, TBPRD, period_cycles);

 	/* Configure ehrpwm counter for up-count mode */
 	ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CTRMODE_MASK,
 		      TBCTL_CTRMODE_UP);

 	if (pwm->hwpwm == 1)
 		/* Channel 1 configured with compare B register */
 		cmp_reg = CMPB;
 	else
 		/* Channel 0 configured with compare A register */
 		cmp_reg = CMPA;

 	ehrpwm_write(pc->mmio_base, cmp_reg, duty_cycles);

 	pm_runtime_put_sync(chip->dev);

 	return 0;
 }

 static int ehrpwm_pwm_set_polarity(struct pwm_chip *chip,
 				   struct pwm_device *pwm,
 				   enum pwm_polarity polarity)
 {
 	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);

 	/* Configuration of polarity in hardware delayed, do at enable */
 	pc->polarity[pwm->hwpwm] = polarity;

 	return 0;
 }

 static int ehrpwm_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
 	u16 aqcsfrc_val, aqcsfrc_mask;
 	int ret;

 	/* Leave clock enabled on enabling PWM */
 	pm_runtime_get_sync(chip->dev);

 	/* Disabling Action Qualifier on PWM output */
 	if (pwm->hwpwm) {
 		aqcsfrc_val = AQCSFRC_CSFB_FRCDIS;
 		aqcsfrc_mask = AQCSFRC_CSFB_MASK;
 	} else {
 		aqcsfrc_val = AQCSFRC_CSFA_FRCDIS;
 		aqcsfrc_mask = AQCSFRC_CSFA_MASK;
 	}

 	/* Changes to shadow mode */
 	ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
 		      AQSFRC_RLDCSF_ZRO);

 	ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);

 	/* Channels polarity can be configured from action qualifier module */
 	configure_polarity(pc, pwm->hwpwm);

 	/* Enable TBCLK */
 	ret = clk_enable(pc->tbclk);
 	if (ret) {
 		dev_err(chip->dev, "Failed to enable TBCLK for %s: %d\n",
 			dev_name(pc->chip.dev), ret);
 		return ret;
 	}

 	return 0;
 }

 static void ehrpwm_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
 	u16 aqcsfrc_val, aqcsfrc_mask;

 	/* Action Qualifier puts PWM output low forcefully */
 	if (pwm->hwpwm) {
 		aqcsfrc_val = AQCSFRC_CSFB_FRCLOW;
 		aqcsfrc_mask = AQCSFRC_CSFB_MASK;
 	} else {
 		aqcsfrc_val = AQCSFRC_CSFA_FRCLOW;
 		aqcsfrc_mask = AQCSFRC_CSFA_MASK;
 	}

 	/* Update shadow register first before modifying active register */
 	ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
 		      AQSFRC_RLDCSF_ZRO);
 	ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);
 	/*
 	 * Changes to immediate action on Action Qualifier. This puts
 	 * Action Qualifier control on PWM output from next TBCLK
 	 */
 	ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
 		      AQSFRC_RLDCSF_IMDT);

 	ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);

 	/* Disabling TBCLK on PWM disable */
 	clk_disable(pc->tbclk);

 	/* Disable clock on PWM disable */
 	pm_runtime_put_sync(chip->dev);
 }

 static void ehrpwm_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);

 	if (pwm_is_enabled(pwm)) {
 		dev_warn(chip->dev, "Removing PWM device without disabling\n");
 		pm_runtime_put_sync(chip->dev);
 	}

 	/* set period value to zero on free */
 	pc->period_cycles[pwm->hwpwm] = 0;
 }

 static int ehrpwm_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			    const struct pwm_state *state)
 {
 	int err;
 	bool enabled = pwm->state.enabled;

 	if (state->polarity != pwm->state.polarity) {
 		if (enabled) {
 			ehrpwm_pwm_disable(chip, pwm);
 			enabled = false;
 		}

 		err = ehrpwm_pwm_set_polarity(chip, pwm, state->polarity);
 		if (err)
 			return err;
 	}

 	if (!state->enabled) {
 		if (enabled)
 			ehrpwm_pwm_disable(chip, pwm);
 		return 0;
 	}

 	err = ehrpwm_pwm_config(chip, pwm, state->duty_cycle, state->period);
 	if (err)
 		return err;

 	if (!enabled)
 		err = ehrpwm_pwm_enable(chip, pwm);

 	return err;
 }

 static const struct pwm_ops ehrpwm_pwm_ops = {
 	.free = ehrpwm_pwm_free,
 	.apply = ehrpwm_pwm_apply,
 	.owner = THIS_MODULE,
 };

 static const struct of_device_id ehrpwm_of_match[] = {
 	{ .compatible = "ti,am3352-ehrpwm" },
 	{ .compatible = "ti,am33xx-ehrpwm" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, ehrpwm_of_match);

 static int ehrpwm_pwm_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct ehrpwm_pwm_chip *pc;
 	struct clk *clk;
 	int ret;

 	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
 	if (!pc)
 		return -ENOMEM;

 	clk = devm_clk_get(&pdev->dev, "fck");
 	if (IS_ERR(clk)) {
 		if (of_device_is_compatible(np, "ti,am33xx-ecap")) {
 			dev_warn(&pdev->dev, "Binding is obsolete.\n");
 			clk = devm_clk_get(pdev->dev.parent, "fck");
 		}
 	}

 	if (IS_ERR(clk))
 		return dev_err_probe(&pdev->dev, PTR_ERR(clk), "Failed to get fck\n");

 	pc->clk_rate = clk_get_rate(clk);
 	if (!pc->clk_rate) {
 		dev_err(&pdev->dev, "failed to get clock rate\n");
 		return -EINVAL;
 	}

 	pc->chip.dev = &pdev->dev;
 	pc->chip.ops = &ehrpwm_pwm_ops;
 	pc->chip.npwm = NUM_PWM_CHANNEL;

 	pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(pc->mmio_base))
 		return PTR_ERR(pc->mmio_base);

 	/* Acquire tbclk for Time Base EHRPWM submodule */
 	pc->tbclk = devm_clk_get(&pdev->dev, "tbclk");
 	if (IS_ERR(pc->tbclk))
 		return dev_err_probe(&pdev->dev, PTR_ERR(pc->tbclk), "Failed to get tbclk\n");

 	ret = clk_prepare(pc->tbclk);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "clk_prepare() failed: %d\n", ret);
 		return ret;
 	}

 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 		goto err_clk_unprepare;
 	}

 	platform_set_drvdata(pdev, pc);
 	pm_runtime_enable(&pdev->dev);

 	return 0;

 err_clk_unprepare:
 	clk_unprepare(pc->tbclk);

 	return ret;
 }

 static int ehrpwm_pwm_remove(struct platform_device *pdev)
 {
 	struct ehrpwm_pwm_chip *pc = platform_get_drvdata(pdev);

 	pwmchip_remove(&pc->chip);

 	clk_unprepare(pc->tbclk);

 	pm_runtime_disable(&pdev->dev);

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static void ehrpwm_pwm_save_context(struct ehrpwm_pwm_chip *pc)
 {
 	pm_runtime_get_sync(pc->chip.dev);

 	pc->ctx.tbctl = ehrpwm_read(pc->mmio_base, TBCTL);
 	pc->ctx.tbprd = ehrpwm_read(pc->mmio_base, TBPRD);
 	pc->ctx.cmpa = ehrpwm_read(pc->mmio_base, CMPA);
 	pc->ctx.cmpb = ehrpwm_read(pc->mmio_base, CMPB);
 	pc->ctx.aqctla = ehrpwm_read(pc->mmio_base, AQCTLA);
 	pc->ctx.aqctlb = ehrpwm_read(pc->mmio_base, AQCTLB);
 	pc->ctx.aqsfrc = ehrpwm_read(pc->mmio_base, AQSFRC);
 	pc->ctx.aqcsfrc = ehrpwm_read(pc->mmio_base, AQCSFRC);

 	pm_runtime_put_sync(pc->chip.dev);
 }

 static void ehrpwm_pwm_restore_context(struct ehrpwm_pwm_chip *pc)
 {
 	ehrpwm_write(pc->mmio_base, TBPRD, pc->ctx.tbprd);
 	ehrpwm_write(pc->mmio_base, CMPA, pc->ctx.cmpa);
 	ehrpwm_write(pc->mmio_base, CMPB, pc->ctx.cmpb);
 	ehrpwm_write(pc->mmio_base, AQCTLA, pc->ctx.aqctla);
 	ehrpwm_write(pc->mmio_base, AQCTLB, pc->ctx.aqctlb);
 	ehrpwm_write(pc->mmio_base, AQSFRC, pc->ctx.aqsfrc);
 	ehrpwm_write(pc->mmio_base, AQCSFRC, pc->ctx.aqcsfrc);
 	ehrpwm_write(pc->mmio_base, TBCTL, pc->ctx.tbctl);
 }

 static int ehrpwm_pwm_suspend(struct device *dev)
 {
 	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
 	unsigned int i;

 	ehrpwm_pwm_save_context(pc);

 	for (i = 0; i < pc->chip.npwm; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];

 		if (!pwm_is_enabled(pwm))
 			continue;

 		/* Disable explicitly if PWM is running */
 		pm_runtime_put_sync(dev);
 	}

 	return 0;
 }

 static int ehrpwm_pwm_resume(struct device *dev)
 {
 	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
 	unsigned int i;

 	for (i = 0; i < pc->chip.npwm; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];

 		if (!pwm_is_enabled(pwm))
 			continue;

 		/* Enable explicitly if PWM was running */
 		pm_runtime_get_sync(dev);
 	}

 	ehrpwm_pwm_restore_context(pc);

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(ehrpwm_pwm_pm_ops, ehrpwm_pwm_suspend,
 			 ehrpwm_pwm_resume);

 static struct platform_driver ehrpwm_pwm_driver = {
 	.driver = {
 		.name = "ehrpwm",
 		.of_match_table = ehrpwm_of_match,
 		.pm = &ehrpwm_pwm_pm_ops,
 	},
 	.probe = ehrpwm_pwm_probe,
 	.remove = ehrpwm_pwm_remove,
 };
 module_platform_driver(ehrpwm_pwm_driver);

 MODULE_DESCRIPTION("EHRPWM PWM driver");
 MODULE_AUTHOR("Texas Instruments");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* EHRPWM PWM driver
	*
	* Copyright (C) 2012 Texas Instruments, Inc. - https://www.ti.com/
	*/

	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/pwm.h>
	#include <linux/io.h>
	#include <linux/err.h>
	#include <linux/clk.h>
	#include <linux/pm_runtime.h>
	#include <linux/of_device.h>

	/* EHRPWM registers and bits definitions */

	/* Time base module registers */
	#define TBCTL 0x00
	#define TBPRD 0x0A

	#define TBCTL_PRDLD_MASK BIT(3)
	#define TBCTL_PRDLD_SHDW 0
	#define TBCTL_PRDLD_IMDT BIT(3)
	#define TBCTL_CLKDIV_MASK (BIT(12) \| BIT(11) \| BIT(10) \| BIT(9) \| \
	BIT(8) \| BIT(7))
	#define TBCTL_CTRMODE_MASK (BIT(1) \| BIT(0))
	#define TBCTL_CTRMODE_UP 0
	#define TBCTL_CTRMODE_DOWN BIT(0)
	#define TBCTL_CTRMODE_UPDOWN BIT(1)
	#define TBCTL_CTRMODE_FREEZE (BIT(1) \| BIT(0))

	#define TBCTL_HSPCLKDIV_SHIFT 7
	#define TBCTL_CLKDIV_SHIFT 10

	#define CLKDIV_MAX 7
	#define HSPCLKDIV_MAX 7
	#define PERIOD_MAX 0xFFFF

	/* compare module registers */
	#define CMPA 0x12
	#define CMPB 0x14

	/* Action qualifier module registers */
	#define AQCTLA 0x16
	#define AQCTLB 0x18
	#define AQSFRC 0x1A
	#define AQCSFRC 0x1C

	#define AQCTL_CBU_MASK (BIT(9) \| BIT(8))
	#define AQCTL_CBU_FRCLOW BIT(8)
	#define AQCTL_CBU_FRCHIGH BIT(9)
	#define AQCTL_CBU_FRCTOGGLE (BIT(9) \| BIT(8))
	#define AQCTL_CAU_MASK (BIT(5) \| BIT(4))
	#define AQCTL_CAU_FRCLOW BIT(4)
	#define AQCTL_CAU_FRCHIGH BIT(5)
	#define AQCTL_CAU_FRCTOGGLE (BIT(5) \| BIT(4))
	#define AQCTL_PRD_MASK (BIT(3) \| BIT(2))
	#define AQCTL_PRD_FRCLOW BIT(2)
	#define AQCTL_PRD_FRCHIGH BIT(3)
	#define AQCTL_PRD_FRCTOGGLE (BIT(3) \| BIT(2))
	#define AQCTL_ZRO_MASK (BIT(1) \| BIT(0))
	#define AQCTL_ZRO_FRCLOW BIT(0)
	#define AQCTL_ZRO_FRCHIGH BIT(1)
	#define AQCTL_ZRO_FRCTOGGLE (BIT(1) \| BIT(0))

	#define AQCTL_CHANA_POLNORMAL (AQCTL_CAU_FRCLOW \| AQCTL_PRD_FRCHIGH \| \
	AQCTL_ZRO_FRCHIGH)
	#define AQCTL_CHANA_POLINVERSED (AQCTL_CAU_FRCHIGH \| AQCTL_PRD_FRCLOW \| \
	AQCTL_ZRO_FRCLOW)
	#define AQCTL_CHANB_POLNORMAL (AQCTL_CBU_FRCLOW \| AQCTL_PRD_FRCHIGH \| \
	AQCTL_ZRO_FRCHIGH)
	#define AQCTL_CHANB_POLINVERSED (AQCTL_CBU_FRCHIGH \| AQCTL_PRD_FRCLOW \| \
	AQCTL_ZRO_FRCLOW)

	#define AQSFRC_RLDCSF_MASK (BIT(7) \| BIT(6))
	#define AQSFRC_RLDCSF_ZRO 0
	#define AQSFRC_RLDCSF_PRD BIT(6)
	#define AQSFRC_RLDCSF_ZROPRD BIT(7)
	#define AQSFRC_RLDCSF_IMDT (BIT(7) \| BIT(6))

	#define AQCSFRC_CSFB_MASK (BIT(3) \| BIT(2))
	#define AQCSFRC_CSFB_FRCDIS 0
	#define AQCSFRC_CSFB_FRCLOW BIT(2)
	#define AQCSFRC_CSFB_FRCHIGH BIT(3)
	#define AQCSFRC_CSFB_DISSWFRC (BIT(3) \| BIT(2))
	#define AQCSFRC_CSFA_MASK (BIT(1) \| BIT(0))
	#define AQCSFRC_CSFA_FRCDIS 0
	#define AQCSFRC_CSFA_FRCLOW BIT(0)
	#define AQCSFRC_CSFA_FRCHIGH BIT(1)
	#define AQCSFRC_CSFA_DISSWFRC (BIT(1) \| BIT(0))

	#define NUM_PWM_CHANNEL 2 /* EHRPWM channels */

	struct ehrpwm_context {
	u16 tbctl;
	u16 tbprd;
	u16 cmpa;
	u16 cmpb;
	u16 aqctla;
	u16 aqctlb;
	u16 aqsfrc;
	u16 aqcsfrc;
	};

	struct ehrpwm_pwm_chip {
	struct pwm_chip chip;
	unsigned long clk_rate;
	void __iomem *mmio_base;
	unsigned long period_cycles[NUM_PWM_CHANNEL];
	enum pwm_polarity polarity[NUM_PWM_CHANNEL];
	struct clk *tbclk;
	struct ehrpwm_context ctx;
	};

	static inline struct ehrpwm_pwm_chip to_ehrpwm_pwm_chip(struct pwm_chip chip)
	{
	return container_of(chip, struct ehrpwm_pwm_chip, chip);
	}

	static inline u16 ehrpwm_read(void __iomem *base, unsigned int offset)
	{
	return readw(base + offset);
	}

	static inline void ehrpwm_write(void __iomem *base, unsigned int offset,
	u16 value)
	{
	writew(value, base + offset);
	}

	static void ehrpwm_modify(void __iomem *base, unsigned int offset, u16 mask,
	u16 value)
	{
	unsigned short val;

	val = readw(base + offset);
	val &= ~mask;
	val \|= value & mask;
	writew(val, base + offset);
	}

	/**
	* set_prescale_div - Set up the prescaler divider function
	* @rqst_prescaler: prescaler value min
	* @prescale_div: prescaler value set
	* @tb_clk_div: Time Base Control prescaler bits
	*/
	static int set_prescale_div(unsigned long rqst_prescaler, u16 *prescale_div,
	u16 *tb_clk_div)
	{
	unsigned int clkdiv, hspclkdiv;

	for (clkdiv = 0; clkdiv <= CLKDIV_MAX; clkdiv++) {
	for (hspclkdiv = 0; hspclkdiv <= HSPCLKDIV_MAX; hspclkdiv++) {
	/*
	* calculations for prescaler value :
	* prescale_div = HSPCLKDIVIDER * CLKDIVIDER.
	* HSPCLKDIVIDER = 2 ** hspclkdiv
	* CLKDIVIDER = (1), if clkdiv == 0 OR
	* (2 * clkdiv), if clkdiv != 0
	*
	* Configure prescale_div value such that period
	* register value is less than 65535.
	*/

	prescale_div = (1 << clkdiv)
	(hspclkdiv ? (hspclkdiv * 2) : 1);
	if (*prescale_div > rqst_prescaler) {
	*tb_clk_div = (clkdiv << TBCTL_CLKDIV_SHIFT) \|
	(hspclkdiv << TBCTL_HSPCLKDIV_SHIFT);
	return 0;
	}
	}
	}

	return 1;
	}

	static void configure_polarity(struct ehrpwm_pwm_chip *pc, int chan)
	{
	u16 aqctl_val, aqctl_mask;
	unsigned int aqctl_reg;

	/*
	* Configure PWM output to HIGH/LOW level on counter
	* reaches compare register value and LOW/HIGH level
	* on counter value reaches period register value and
	* zero value on counter
	*/
	if (chan == 1) {
	aqctl_reg = AQCTLB;
	aqctl_mask = AQCTL_CBU_MASK;

	if (pc->polarity[chan] == PWM_POLARITY_INVERSED)
	aqctl_val = AQCTL_CHANB_POLINVERSED;
	else
	aqctl_val = AQCTL_CHANB_POLNORMAL;
	} else {
	aqctl_reg = AQCTLA;
	aqctl_mask = AQCTL_CAU_MASK;

	if (pc->polarity[chan] == PWM_POLARITY_INVERSED)
	aqctl_val = AQCTL_CHANA_POLINVERSED;
	else
	aqctl_val = AQCTL_CHANA_POLNORMAL;
	}

	aqctl_mask \|= AQCTL_PRD_MASK \| AQCTL_ZRO_MASK;
	ehrpwm_modify(pc->mmio_base, aqctl_reg, aqctl_mask, aqctl_val);
	}

	/*
	* period_ns = 10^9 * (ps_divval * period_cycles) / PWM_CLK_RATE
	* duty_ns = 10^9 * (ps_divval * duty_cycles) / PWM_CLK_RATE
	*/
	static int ehrpwm_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
	u64 duty_ns, u64 period_ns)
	{
	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
	u32 period_cycles, duty_cycles;
	u16 ps_divval, tb_divval;
	unsigned int i, cmp_reg;
	unsigned long long c;

	if (period_ns > NSEC_PER_SEC)
	return -ERANGE;

	c = pc->clk_rate;
	c = c * period_ns;
	do_div(c, NSEC_PER_SEC);
	period_cycles = (unsigned long)c;

	if (period_cycles < 1) {
	period_cycles = 1;
	duty_cycles = 1;
	} else {
	c = pc->clk_rate;
	c = c * duty_ns;
	do_div(c, NSEC_PER_SEC);
	duty_cycles = (unsigned long)c;
	}

	/*
	* Period values should be same for multiple PWM channels as IP uses
	* same period register for multiple channels.
	*/
	for (i = 0; i < NUM_PWM_CHANNEL; i++) {
	if (pc->period_cycles[i] &&
	(pc->period_cycles[i] != period_cycles)) {
	/*
	* Allow channel to reconfigure period if no other
	* channels being configured.
	*/
	if (i == pwm->hwpwm)
	continue;

	dev_err(chip->dev,
	"period value conflicts with channel %u\n",
	i);
	return -EINVAL;
	}
	}

	pc->period_cycles[pwm->hwpwm] = period_cycles;

	/* Configure clock prescaler to support Low frequency PWM wave */
	if (set_prescale_div(period_cycles/PERIOD_MAX, &ps_divval,
	&tb_divval)) {
	dev_err(chip->dev, "Unsupported values\n");
	return -EINVAL;
	}

	pm_runtime_get_sync(chip->dev);

	/* Update clock prescaler values */
	ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CLKDIV_MASK, tb_divval);

	/* Update period & duty cycle with presacler division */
	period_cycles = period_cycles / ps_divval;
	duty_cycles = duty_cycles / ps_divval;

	/* Configure shadow loading on Period register */
	ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_PRDLD_MASK, TBCTL_PRDLD_SHDW);

	ehrpwm_write(pc->mmio_base, TBPRD, period_cycles);

	/* Configure ehrpwm counter for up-count mode */
	ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CTRMODE_MASK,
	TBCTL_CTRMODE_UP);

	if (pwm->hwpwm == 1)
	/* Channel 1 configured with compare B register */
	cmp_reg = CMPB;
	else
	/* Channel 0 configured with compare A register */
	cmp_reg = CMPA;

	ehrpwm_write(pc->mmio_base, cmp_reg, duty_cycles);

	pm_runtime_put_sync(chip->dev);

	return 0;
	}

	static int ehrpwm_pwm_set_polarity(struct pwm_chip *chip,
	struct pwm_device *pwm,
	enum pwm_polarity polarity)
	{
	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);

	/* Configuration of polarity in hardware delayed, do at enable */
	pc->polarity[pwm->hwpwm] = polarity;

	return 0;
	}

	static int ehrpwm_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
	u16 aqcsfrc_val, aqcsfrc_mask;
	int ret;

	/* Leave clock enabled on enabling PWM */
	pm_runtime_get_sync(chip->dev);

	/* Disabling Action Qualifier on PWM output */
	if (pwm->hwpwm) {
	aqcsfrc_val = AQCSFRC_CSFB_FRCDIS;
	aqcsfrc_mask = AQCSFRC_CSFB_MASK;
	} else {
	aqcsfrc_val = AQCSFRC_CSFA_FRCDIS;
	aqcsfrc_mask = AQCSFRC_CSFA_MASK;
	}

	/* Changes to shadow mode */
	ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
	AQSFRC_RLDCSF_ZRO);

	ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);

	/* Channels polarity can be configured from action qualifier module */
	configure_polarity(pc, pwm->hwpwm);

	/* Enable TBCLK */
	ret = clk_enable(pc->tbclk);
	if (ret) {
	dev_err(chip->dev, "Failed to enable TBCLK for %s: %d\n",
	dev_name(pc->chip.dev), ret);
	return ret;
	}

	return 0;
	}

	static void ehrpwm_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
	u16 aqcsfrc_val, aqcsfrc_mask;

	/* Action Qualifier puts PWM output low forcefully */
	if (pwm->hwpwm) {
	aqcsfrc_val = AQCSFRC_CSFB_FRCLOW;
	aqcsfrc_mask = AQCSFRC_CSFB_MASK;
	} else {
	aqcsfrc_val = AQCSFRC_CSFA_FRCLOW;
	aqcsfrc_mask = AQCSFRC_CSFA_MASK;
	}

	/* Update shadow register first before modifying active register */
	ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
	AQSFRC_RLDCSF_ZRO);
	ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);
	/*
	* Changes to immediate action on Action Qualifier. This puts
	* Action Qualifier control on PWM output from next TBCLK
	*/
	ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
	AQSFRC_RLDCSF_IMDT);

	ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);

	/* Disabling TBCLK on PWM disable */
	clk_disable(pc->tbclk);

	/* Disable clock on PWM disable */
	pm_runtime_put_sync(chip->dev);
	}

	static void ehrpwm_pwm_free(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);

	if (pwm_is_enabled(pwm)) {
	dev_warn(chip->dev, "Removing PWM device without disabling\n");
	pm_runtime_put_sync(chip->dev);
	}

	/* set period value to zero on free */
	pc->period_cycles[pwm->hwpwm] = 0;
	}

	static int ehrpwm_pwm_apply(struct pwm_chip chip, struct pwm_device pwm,
	const struct pwm_state *state)
	{
	int err;
	bool enabled = pwm->state.enabled;

	if (state->polarity != pwm->state.polarity) {
	if (enabled) {
	ehrpwm_pwm_disable(chip, pwm);
	enabled = false;
	}

	err = ehrpwm_pwm_set_polarity(chip, pwm, state->polarity);
	if (err)
	return err;
	}

	if (!state->enabled) {
	if (enabled)
	ehrpwm_pwm_disable(chip, pwm);
	return 0;
	}

	err = ehrpwm_pwm_config(chip, pwm, state->duty_cycle, state->period);
	if (err)
	return err;

	if (!enabled)
	err = ehrpwm_pwm_enable(chip, pwm);

	return err;
	}

	static const struct pwm_ops ehrpwm_pwm_ops = {
	.free = ehrpwm_pwm_free,
	.apply = ehrpwm_pwm_apply,
	.owner = THIS_MODULE,
	};

	static const struct of_device_id ehrpwm_of_match[] = {
	{ .compatible = "ti,am3352-ehrpwm" },
	{ .compatible = "ti,am33xx-ehrpwm" },
	{},
	};
	MODULE_DEVICE_TABLE(of, ehrpwm_of_match);

	static int ehrpwm_pwm_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	struct ehrpwm_pwm_chip *pc;
	struct clk *clk;
	int ret;

	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
	if (!pc)
	return -ENOMEM;

	clk = devm_clk_get(&pdev->dev, "fck");
	if (IS_ERR(clk)) {
	if (of_device_is_compatible(np, "ti,am33xx-ecap")) {
	dev_warn(&pdev->dev, "Binding is obsolete.\n");
	clk = devm_clk_get(pdev->dev.parent, "fck");
	}
	}

	if (IS_ERR(clk))
	return dev_err_probe(&pdev->dev, PTR_ERR(clk), "Failed to get fck\n");

	pc->clk_rate = clk_get_rate(clk);
	if (!pc->clk_rate) {
	dev_err(&pdev->dev, "failed to get clock rate\n");
	return -EINVAL;
	}

	pc->chip.dev = &pdev->dev;
	pc->chip.ops = &ehrpwm_pwm_ops;
	pc->chip.npwm = NUM_PWM_CHANNEL;

	pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(pc->mmio_base))
	return PTR_ERR(pc->mmio_base);

	/* Acquire tbclk for Time Base EHRPWM submodule */
	pc->tbclk = devm_clk_get(&pdev->dev, "tbclk");
	if (IS_ERR(pc->tbclk))
	return dev_err_probe(&pdev->dev, PTR_ERR(pc->tbclk), "Failed to get tbclk\n");

	ret = clk_prepare(pc->tbclk);
	if (ret < 0) {
	dev_err(&pdev->dev, "clk_prepare() failed: %d\n", ret);
	return ret;
	}

	ret = pwmchip_add(&pc->chip);
	if (ret < 0) {
	dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
	goto err_clk_unprepare;
	}

	platform_set_drvdata(pdev, pc);
	pm_runtime_enable(&pdev->dev);

	return 0;

	err_clk_unprepare:
	clk_unprepare(pc->tbclk);

	return ret;
	}

	static int ehrpwm_pwm_remove(struct platform_device *pdev)
	{
	struct ehrpwm_pwm_chip *pc = platform_get_drvdata(pdev);

	pwmchip_remove(&pc->chip);

	clk_unprepare(pc->tbclk);

	pm_runtime_disable(&pdev->dev);

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static void ehrpwm_pwm_save_context(struct ehrpwm_pwm_chip *pc)
	{
	pm_runtime_get_sync(pc->chip.dev);

	pc->ctx.tbctl = ehrpwm_read(pc->mmio_base, TBCTL);
	pc->ctx.tbprd = ehrpwm_read(pc->mmio_base, TBPRD);
	pc->ctx.cmpa = ehrpwm_read(pc->mmio_base, CMPA);
	pc->ctx.cmpb = ehrpwm_read(pc->mmio_base, CMPB);
	pc->ctx.aqctla = ehrpwm_read(pc->mmio_base, AQCTLA);
	pc->ctx.aqctlb = ehrpwm_read(pc->mmio_base, AQCTLB);
	pc->ctx.aqsfrc = ehrpwm_read(pc->mmio_base, AQSFRC);
	pc->ctx.aqcsfrc = ehrpwm_read(pc->mmio_base, AQCSFRC);

	pm_runtime_put_sync(pc->chip.dev);
	}

	static void ehrpwm_pwm_restore_context(struct ehrpwm_pwm_chip *pc)
	{
	ehrpwm_write(pc->mmio_base, TBPRD, pc->ctx.tbprd);
	ehrpwm_write(pc->mmio_base, CMPA, pc->ctx.cmpa);
	ehrpwm_write(pc->mmio_base, CMPB, pc->ctx.cmpb);
	ehrpwm_write(pc->mmio_base, AQCTLA, pc->ctx.aqctla);
	ehrpwm_write(pc->mmio_base, AQCTLB, pc->ctx.aqctlb);
	ehrpwm_write(pc->mmio_base, AQSFRC, pc->ctx.aqsfrc);
	ehrpwm_write(pc->mmio_base, AQCSFRC, pc->ctx.aqcsfrc);
	ehrpwm_write(pc->mmio_base, TBCTL, pc->ctx.tbctl);
	}

	static int ehrpwm_pwm_suspend(struct device *dev)
	{
	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
	unsigned int i;

	ehrpwm_pwm_save_context(pc);

	for (i = 0; i < pc->chip.npwm; i++) {
	struct pwm_device *pwm = &pc->chip.pwms[i];

	if (!pwm_is_enabled(pwm))
	continue;

	/* Disable explicitly if PWM is running */
	pm_runtime_put_sync(dev);
	}

	return 0;
	}

	static int ehrpwm_pwm_resume(struct device *dev)
	{
	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
	unsigned int i;

	for (i = 0; i < pc->chip.npwm; i++) {
	struct pwm_device *pwm = &pc->chip.pwms[i];

	if (!pwm_is_enabled(pwm))
	continue;

	/* Enable explicitly if PWM was running */
	pm_runtime_get_sync(dev);
	}

	ehrpwm_pwm_restore_context(pc);

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(ehrpwm_pwm_pm_ops, ehrpwm_pwm_suspend,
	ehrpwm_pwm_resume);

	static struct platform_driver ehrpwm_pwm_driver = {
	.driver = {
	.name = "ehrpwm",
	.of_match_table = ehrpwm_of_match,
	.pm = &ehrpwm_pwm_pm_ops,
	},
	.probe = ehrpwm_pwm_probe,
	.remove = ehrpwm_pwm_remove,
	};
	module_platform_driver(ehrpwm_pwm_driver);

	MODULE_DESCRIPTION("EHRPWM PWM driver");
	MODULE_AUTHOR("Texas Instruments");
	MODULE_LICENSE("GPL");