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	pwm: atmel: add Timer Counter Block PWM driver
This patch adds a PWM driver based on Atmel Timer Counter Block. The Timer Counter Block is used in Waveform generator mode. A Timer Counter Block provides up to 6 PWM devices grouped by 2: * group 0 = PWM 0 and 1 * group 1 = PWM 2 and 3 * group 2 = PMW 4 and 5 PWM devices in a given group must be configured with the same period value. If a PWM device in a group tries to change the period value and the other device is already configured with a different value an error will be returned. This driver requires device tree support. The Timer Counter Block number used to create a PWM chip is given by the tc-block field in an "atmel,tcb-pwm" compatible node. This patch was tested on kizbox board (at91sam9g20 SoC) with pwm-leds. Signed-off-by: Boris BREZILLON <linux-arm@overkiz.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
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										18
									
								
								Documentation/devicetree/bindings/pwm/atmel-tcb-pwm.txt
									
									
									
									
									
										Normal file
									
								
							
							
						
						
									
										18
									
								
								Documentation/devicetree/bindings/pwm/atmel-tcb-pwm.txt
									
									
									
									
									
										Normal file
									
								
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			@ -0,0 +1,18 @@
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Atmel TCB PWM controller
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Required properties:
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- compatible: should be "atmel,tcb-pwm"
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- #pwm-cells: Should be 3.  The first cell specifies the per-chip index
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  of the PWM to use, the second cell is the period in nanoseconds and
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  bit 0 in the third cell is used to encode the polarity of PWM output.
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  Set bit 0 of the third cell in PWM specifier to 1 for inverse polarity &
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  set to 0 for normal polarity.
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- tc-block: The Timer Counter block to use as a PWM chip.
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Example:
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pwm {
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	compatible = "atmel,tcb-pwm";
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	#pwm-cells = <3>;
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	tc-block = <1>;
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};
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| 
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			@ -37,6 +37,18 @@ config PWM_AB8500
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	  To compile this driver as a module, choose M here: the module
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	  will be called pwm-ab8500.
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config PWM_ATMEL_TCB
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	tristate "TC Block PWM"
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	depends on ATMEL_TCLIB && OF
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	help
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	  Generic PWM framework driver for Atmel Timer Counter Block.
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	  A Timer Counter Block provides 6 PWM devices grouped by 2.
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	  Devices in a given group must have the same period.
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	  To compile this driver as a module, choose M here: the module
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	  will be called pwm-atmel-tcb.
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config PWM_BFIN
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	tristate "Blackfin PWM support"
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	depends on BFIN_GPTIMERS
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			@ -1,5 +1,6 @@
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obj-$(CONFIG_PWM)		+= core.o
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obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
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obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
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obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
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obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
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obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
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| 
						 | 
				
			
			
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		|||
							
								
								
									
										445
									
								
								drivers/pwm/pwm-atmel-tcb.c
									
									
									
									
									
										Normal file
									
								
							
							
						
						
									
										445
									
								
								drivers/pwm/pwm-atmel-tcb.c
									
									
									
									
									
										Normal file
									
								
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			@ -0,0 +1,445 @@
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/*
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 * Copyright (C) Overkiz SAS 2012
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 *
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 * Author: Boris BREZILLON <b.brezillon@overkiz.com>
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 * License terms: GNU General Public License (GPL) version 2
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 */
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/ioport.h>
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#include <linux/io.h>
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#include <linux/platform_device.h>
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#include <linux/atmel_tc.h>
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#include <linux/pwm.h>
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#include <linux/of_device.h>
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#include <linux/slab.h>
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#define NPWM	6
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#define ATMEL_TC_ACMR_MASK	(ATMEL_TC_ACPA | ATMEL_TC_ACPC |	\
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				 ATMEL_TC_AEEVT | ATMEL_TC_ASWTRG)
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#define ATMEL_TC_BCMR_MASK	(ATMEL_TC_BCPB | ATMEL_TC_BCPC |	\
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				 ATMEL_TC_BEEVT | ATMEL_TC_BSWTRG)
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struct atmel_tcb_pwm_device {
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	enum pwm_polarity polarity;	/* PWM polarity */
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	unsigned div;			/* PWM clock divider */
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	unsigned duty;			/* PWM duty expressed in clk cycles */
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	unsigned period;		/* PWM period expressed in clk cycles */
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};
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struct atmel_tcb_pwm_chip {
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	struct pwm_chip chip;
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	spinlock_t lock;
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	struct atmel_tc *tc;
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	struct atmel_tcb_pwm_device *pwms[NPWM];
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};
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static inline struct atmel_tcb_pwm_chip *to_tcb_chip(struct pwm_chip *chip)
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{
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	return container_of(chip, struct atmel_tcb_pwm_chip, chip);
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}
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static int atmel_tcb_pwm_set_polarity(struct pwm_chip *chip,
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				      struct pwm_device *pwm,
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				      enum pwm_polarity polarity)
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{
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	struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
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	tcbpwm->polarity = polarity;
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	return 0;
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}
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static int atmel_tcb_pwm_request(struct pwm_chip *chip,
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				 struct pwm_device *pwm)
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{
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	struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
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	struct atmel_tcb_pwm_device *tcbpwm;
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	struct atmel_tc *tc = tcbpwmc->tc;
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	void __iomem *regs = tc->regs;
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	unsigned group = pwm->hwpwm / 2;
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	unsigned index = pwm->hwpwm % 2;
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	unsigned cmr;
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	int ret;
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	tcbpwm = devm_kzalloc(chip->dev, sizeof(*tcbpwm), GFP_KERNEL);
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	if (!tcbpwm)
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		return -ENOMEM;
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	ret = clk_enable(tc->clk[group]);
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	if (ret) {
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		devm_kfree(chip->dev, tcbpwm);
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		return ret;
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	}
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	pwm_set_chip_data(pwm, tcbpwm);
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	tcbpwm->polarity = PWM_POLARITY_NORMAL;
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	tcbpwm->duty = 0;
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	tcbpwm->period = 0;
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	tcbpwm->div = 0;
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	spin_lock(&tcbpwmc->lock);
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	cmr = __raw_readl(regs + ATMEL_TC_REG(group, CMR));
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	/*
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	 * Get init config from Timer Counter registers if
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	 * Timer Counter is already configured as a PWM generator.
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	 */
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	if (cmr & ATMEL_TC_WAVE) {
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		if (index == 0)
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			tcbpwm->duty =
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				__raw_readl(regs + ATMEL_TC_REG(group, RA));
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		else
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			tcbpwm->duty =
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				__raw_readl(regs + ATMEL_TC_REG(group, RB));
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		tcbpwm->div = cmr & ATMEL_TC_TCCLKS;
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		tcbpwm->period = __raw_readl(regs + ATMEL_TC_REG(group, RC));
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		cmr &= (ATMEL_TC_TCCLKS | ATMEL_TC_ACMR_MASK |
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			ATMEL_TC_BCMR_MASK);
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	} else
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		cmr = 0;
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	cmr |= ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO | ATMEL_TC_EEVT_XC0;
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	__raw_writel(cmr, regs + ATMEL_TC_REG(group, CMR));
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	spin_unlock(&tcbpwmc->lock);
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	tcbpwmc->pwms[pwm->hwpwm] = tcbpwm;
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	return 0;
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}
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static void atmel_tcb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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	struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
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	struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
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	struct atmel_tc *tc = tcbpwmc->tc;
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	clk_disable(tc->clk[pwm->hwpwm / 2]);
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	tcbpwmc->pwms[pwm->hwpwm] = NULL;
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	devm_kfree(chip->dev, tcbpwm);
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}
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static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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	struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
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	struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
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	struct atmel_tc *tc = tcbpwmc->tc;
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	void __iomem *regs = tc->regs;
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	unsigned group = pwm->hwpwm / 2;
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	unsigned index = pwm->hwpwm % 2;
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	unsigned cmr;
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	enum pwm_polarity polarity = tcbpwm->polarity;
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	/*
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	 * If duty is 0 the timer will be stopped and we have to
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	 * configure the output correctly on software trigger:
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	 *  - set output to high if PWM_POLARITY_INVERSED
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	 *  - set output to low if PWM_POLARITY_NORMAL
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	 *
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	 * This is why we're reverting polarity in this case.
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	 */
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	if (tcbpwm->duty == 0)
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		polarity = !polarity;
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	spin_lock(&tcbpwmc->lock);
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	cmr = __raw_readl(regs + ATMEL_TC_REG(group, CMR));
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	/* flush old setting and set the new one */
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	if (index == 0) {
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		cmr &= ~ATMEL_TC_ACMR_MASK;
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		if (polarity == PWM_POLARITY_INVERSED)
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			cmr |= ATMEL_TC_ASWTRG_CLEAR;
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		else
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			cmr |= ATMEL_TC_ASWTRG_SET;
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	} else {
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		cmr &= ~ATMEL_TC_BCMR_MASK;
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		if (polarity == PWM_POLARITY_INVERSED)
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			cmr |= ATMEL_TC_BSWTRG_CLEAR;
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		else
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			cmr |= ATMEL_TC_BSWTRG_SET;
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	}
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	__raw_writel(cmr, regs + ATMEL_TC_REG(group, CMR));
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	/*
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	 * Use software trigger to apply the new setting.
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	 * If both PWM devices in this group are disabled we stop the clock.
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	 */
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	if (!(cmr & (ATMEL_TC_ACPC | ATMEL_TC_BCPC)))
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		__raw_writel(ATMEL_TC_SWTRG | ATMEL_TC_CLKDIS,
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			     regs + ATMEL_TC_REG(group, CCR));
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	else
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		__raw_writel(ATMEL_TC_SWTRG, regs +
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			     ATMEL_TC_REG(group, CCR));
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	spin_unlock(&tcbpwmc->lock);
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}
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static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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	struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
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	struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
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	struct atmel_tc *tc = tcbpwmc->tc;
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	void __iomem *regs = tc->regs;
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	unsigned group = pwm->hwpwm / 2;
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	unsigned index = pwm->hwpwm % 2;
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	u32 cmr;
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	enum pwm_polarity polarity = tcbpwm->polarity;
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	/*
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	 * If duty is 0 the timer will be stopped and we have to
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	 * configure the output correctly on software trigger:
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	 *  - set output to high if PWM_POLARITY_INVERSED
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	 *  - set output to low if PWM_POLARITY_NORMAL
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	 *
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	 * This is why we're reverting polarity in this case.
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	 */
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	if (tcbpwm->duty == 0)
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		polarity = !polarity;
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	spin_lock(&tcbpwmc->lock);
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	cmr = __raw_readl(regs + ATMEL_TC_REG(group, CMR));
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	/* flush old setting and set the new one */
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	cmr &= ~ATMEL_TC_TCCLKS;
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	if (index == 0) {
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		cmr &= ~ATMEL_TC_ACMR_MASK;
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		/* Set CMR flags according to given polarity */
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		if (polarity == PWM_POLARITY_INVERSED)
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			cmr |= ATMEL_TC_ASWTRG_CLEAR;
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		else
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			cmr |= ATMEL_TC_ASWTRG_SET;
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	} else {
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		cmr &= ~ATMEL_TC_BCMR_MASK;
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		if (polarity == PWM_POLARITY_INVERSED)
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			cmr |= ATMEL_TC_BSWTRG_CLEAR;
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		else
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			cmr |= ATMEL_TC_BSWTRG_SET;
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	}
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	/*
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	 * If duty is 0 or equal to period there's no need to register
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	 * a specific action on RA/RB and RC compare.
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	 * The output will be configured on software trigger and keep
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	 * this config till next config call.
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	 */
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	if (tcbpwm->duty != tcbpwm->period && tcbpwm->duty > 0) {
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		if (index == 0) {
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			if (polarity == PWM_POLARITY_INVERSED)
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				cmr |= ATMEL_TC_ACPA_SET | ATMEL_TC_ACPC_CLEAR;
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			else
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				cmr |= ATMEL_TC_ACPA_CLEAR | ATMEL_TC_ACPC_SET;
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		} else {
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			if (polarity == PWM_POLARITY_INVERSED)
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				cmr |= ATMEL_TC_BCPB_SET | ATMEL_TC_BCPC_CLEAR;
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			else
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				cmr |= ATMEL_TC_BCPB_CLEAR | ATMEL_TC_BCPC_SET;
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		}
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	}
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	__raw_writel(cmr, regs + ATMEL_TC_REG(group, CMR));
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	if (index == 0)
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		__raw_writel(tcbpwm->duty, regs + ATMEL_TC_REG(group, RA));
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	else
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		__raw_writel(tcbpwm->duty, regs + ATMEL_TC_REG(group, RB));
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	__raw_writel(tcbpwm->period, regs + ATMEL_TC_REG(group, RC));
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	/* Use software trigger to apply the new setting */
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	__raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
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		     regs + ATMEL_TC_REG(group, CCR));
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	spin_unlock(&tcbpwmc->lock);
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	return 0;
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}
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static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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		||||
				int duty_ns, int period_ns)
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		||||
{
 | 
			
		||||
	struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 | 
			
		||||
	struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
 | 
			
		||||
	unsigned group = pwm->hwpwm / 2;
 | 
			
		||||
	unsigned index = pwm->hwpwm % 2;
 | 
			
		||||
	struct atmel_tcb_pwm_device *atcbpwm = NULL;
 | 
			
		||||
	struct atmel_tc *tc = tcbpwmc->tc;
 | 
			
		||||
	int i;
 | 
			
		||||
	int slowclk = 0;
 | 
			
		||||
	unsigned period;
 | 
			
		||||
	unsigned duty;
 | 
			
		||||
	unsigned rate = clk_get_rate(tc->clk[group]);
 | 
			
		||||
	unsigned long long min;
 | 
			
		||||
	unsigned long long max;
 | 
			
		||||
 | 
			
		||||
	/*
 | 
			
		||||
	 * Find best clk divisor:
 | 
			
		||||
	 * the smallest divisor which can fulfill the period_ns requirements.
 | 
			
		||||
	 */
 | 
			
		||||
	for (i = 0; i < 5; ++i) {
 | 
			
		||||
		if (atmel_tc_divisors[i] == 0) {
 | 
			
		||||
			slowclk = i;
 | 
			
		||||
			continue;
 | 
			
		||||
		}
 | 
			
		||||
		min = div_u64((u64)NSEC_PER_SEC * atmel_tc_divisors[i], rate);
 | 
			
		||||
		max = min << tc->tcb_config->counter_width;
 | 
			
		||||
		if (max >= period_ns)
 | 
			
		||||
			break;
 | 
			
		||||
	}
 | 
			
		||||
 | 
			
		||||
	/*
 | 
			
		||||
	 * If none of the divisor are small enough to represent period_ns
 | 
			
		||||
	 * take slow clock (32KHz).
 | 
			
		||||
	 */
 | 
			
		||||
	if (i == 5) {
 | 
			
		||||
		i = slowclk;
 | 
			
		||||
		rate = 32768;
 | 
			
		||||
		min = div_u64(NSEC_PER_SEC, rate);
 | 
			
		||||
		max = min << 16;
 | 
			
		||||
 | 
			
		||||
		/* If period is too big return ERANGE error */
 | 
			
		||||
		if (max < period_ns)
 | 
			
		||||
			return -ERANGE;
 | 
			
		||||
	}
 | 
			
		||||
 | 
			
		||||
	duty = div_u64(duty_ns, min);
 | 
			
		||||
	period = div_u64(period_ns, min);
 | 
			
		||||
 | 
			
		||||
	if (index == 0)
 | 
			
		||||
		atcbpwm = tcbpwmc->pwms[pwm->hwpwm + 1];
 | 
			
		||||
	else
 | 
			
		||||
		atcbpwm = tcbpwmc->pwms[pwm->hwpwm - 1];
 | 
			
		||||
 | 
			
		||||
	/*
 | 
			
		||||
	 * PWM devices provided by TCB driver are grouped by 2:
 | 
			
		||||
	 * - group 0: PWM 0 & 1
 | 
			
		||||
	 * - group 1: PWM 2 & 3
 | 
			
		||||
	 * - group 2: PWM 4 & 5
 | 
			
		||||
	 *
 | 
			
		||||
	 * PWM devices in a given group must be configured with the
 | 
			
		||||
	 * same period_ns.
 | 
			
		||||
	 *
 | 
			
		||||
	 * We're checking the period value of the second PWM device
 | 
			
		||||
	 * in this group before applying the new config.
 | 
			
		||||
	 */
 | 
			
		||||
	if ((atcbpwm && atcbpwm->duty > 0 &&
 | 
			
		||||
			atcbpwm->duty != atcbpwm->period) &&
 | 
			
		||||
		(atcbpwm->div != i || atcbpwm->period != period)) {
 | 
			
		||||
		dev_err(chip->dev,
 | 
			
		||||
			"failed to configure period_ns: PWM group already configured with a different value\n");
 | 
			
		||||
		return -EINVAL;
 | 
			
		||||
	}
 | 
			
		||||
 | 
			
		||||
	tcbpwm->period = period;
 | 
			
		||||
	tcbpwm->div = i;
 | 
			
		||||
	tcbpwm->duty = duty;
 | 
			
		||||
 | 
			
		||||
	/* If the PWM is enabled, call enable to apply the new conf */
 | 
			
		||||
	if (test_bit(PWMF_ENABLED, &pwm->flags))
 | 
			
		||||
		atmel_tcb_pwm_enable(chip, pwm);
 | 
			
		||||
 | 
			
		||||
	return 0;
 | 
			
		||||
}
 | 
			
		||||
 | 
			
		||||
static const struct pwm_ops atmel_tcb_pwm_ops = {
 | 
			
		||||
	.request = atmel_tcb_pwm_request,
 | 
			
		||||
	.free = atmel_tcb_pwm_free,
 | 
			
		||||
	.config = atmel_tcb_pwm_config,
 | 
			
		||||
	.set_polarity = atmel_tcb_pwm_set_polarity,
 | 
			
		||||
	.enable = atmel_tcb_pwm_enable,
 | 
			
		||||
	.disable = atmel_tcb_pwm_disable,
 | 
			
		||||
};
 | 
			
		||||
 | 
			
		||||
static int atmel_tcb_pwm_probe(struct platform_device *pdev)
 | 
			
		||||
{
 | 
			
		||||
	struct atmel_tcb_pwm_chip *tcbpwm;
 | 
			
		||||
	struct device_node *np = pdev->dev.of_node;
 | 
			
		||||
	struct atmel_tc *tc;
 | 
			
		||||
	int err;
 | 
			
		||||
	int tcblock;
 | 
			
		||||
 | 
			
		||||
	err = of_property_read_u32(np, "tc-block", &tcblock);
 | 
			
		||||
	if (err < 0) {
 | 
			
		||||
		dev_err(&pdev->dev,
 | 
			
		||||
			"failed to get Timer Counter Block number from device tree (error: %d)\n",
 | 
			
		||||
			err);
 | 
			
		||||
		return err;
 | 
			
		||||
	}
 | 
			
		||||
 | 
			
		||||
	tc = atmel_tc_alloc(tcblock, "tcb-pwm");
 | 
			
		||||
	if (tc == NULL) {
 | 
			
		||||
		dev_err(&pdev->dev, "failed to allocate Timer Counter Block\n");
 | 
			
		||||
		return -ENOMEM;
 | 
			
		||||
	}
 | 
			
		||||
 | 
			
		||||
	tcbpwm = devm_kzalloc(&pdev->dev, sizeof(*tcbpwm), GFP_KERNEL);
 | 
			
		||||
	if (tcbpwm == NULL) {
 | 
			
		||||
		atmel_tc_free(tc);
 | 
			
		||||
		dev_err(&pdev->dev, "failed to allocate memory\n");
 | 
			
		||||
		return -ENOMEM;
 | 
			
		||||
	}
 | 
			
		||||
 | 
			
		||||
	tcbpwm->chip.dev = &pdev->dev;
 | 
			
		||||
	tcbpwm->chip.ops = &atmel_tcb_pwm_ops;
 | 
			
		||||
	tcbpwm->chip.of_xlate = of_pwm_xlate_with_flags;
 | 
			
		||||
	tcbpwm->chip.of_pwm_n_cells = 3;
 | 
			
		||||
	tcbpwm->chip.base = -1;
 | 
			
		||||
	tcbpwm->chip.npwm = NPWM;
 | 
			
		||||
	tcbpwm->tc = tc;
 | 
			
		||||
 | 
			
		||||
	spin_lock_init(&tcbpwm->lock);
 | 
			
		||||
 | 
			
		||||
	err = pwmchip_add(&tcbpwm->chip);
 | 
			
		||||
	if (err < 0) {
 | 
			
		||||
		atmel_tc_free(tc);
 | 
			
		||||
		return err;
 | 
			
		||||
	}
 | 
			
		||||
 | 
			
		||||
	platform_set_drvdata(pdev, tcbpwm);
 | 
			
		||||
 | 
			
		||||
	return 0;
 | 
			
		||||
}
 | 
			
		||||
 | 
			
		||||
static int atmel_tcb_pwm_remove(struct platform_device *pdev)
 | 
			
		||||
{
 | 
			
		||||
	struct atmel_tcb_pwm_chip *tcbpwm = platform_get_drvdata(pdev);
 | 
			
		||||
	int err;
 | 
			
		||||
 | 
			
		||||
	err = pwmchip_remove(&tcbpwm->chip);
 | 
			
		||||
	if (err < 0)
 | 
			
		||||
		return err;
 | 
			
		||||
 | 
			
		||||
	atmel_tc_free(tcbpwm->tc);
 | 
			
		||||
 | 
			
		||||
	return 0;
 | 
			
		||||
}
 | 
			
		||||
 | 
			
		||||
static const struct of_device_id atmel_tcb_pwm_dt_ids[] = {
 | 
			
		||||
	{ .compatible = "atmel,tcb-pwm", },
 | 
			
		||||
	{ /* sentinel */ }
 | 
			
		||||
};
 | 
			
		||||
MODULE_DEVICE_TABLE(of, atmel_tcb_pwm_dt_ids);
 | 
			
		||||
 | 
			
		||||
static struct platform_driver atmel_tcb_pwm_driver = {
 | 
			
		||||
	.driver = {
 | 
			
		||||
		.name = "atmel-tcb-pwm",
 | 
			
		||||
		.of_match_table = atmel_tcb_pwm_dt_ids,
 | 
			
		||||
	},
 | 
			
		||||
	.probe = atmel_tcb_pwm_probe,
 | 
			
		||||
	.remove = atmel_tcb_pwm_remove,
 | 
			
		||||
};
 | 
			
		||||
module_platform_driver(atmel_tcb_pwm_driver);
 | 
			
		||||
 | 
			
		||||
MODULE_AUTHOR("Boris BREZILLON <b.brezillon@overkiz.com>");
 | 
			
		||||
MODULE_DESCRIPTION("Atmel Timer Counter Pulse Width Modulation Driver");
 | 
			
		||||
MODULE_LICENSE("GPL v2");
 | 
			
		||||
		Loading…
	
		Reference in a new issue