1 /* 2 * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; version 2. 7 */ 8 9 #include <linux/clk.h> 10 #include <linux/err.h> 11 #include <linux/io.h> 12 #include <linux/module.h> 13 #include <linux/of.h> 14 #include <linux/platform_device.h> 15 #include <linux/pwm.h> 16 17 #define PWM_CONTROL 0x000 18 #define PWM_CONTROL_SHIFT(x) ((x) * 8) 19 #define PWM_CONTROL_MASK 0xff 20 #define PWM_MODE 0x80 /* set timer in PWM mode */ 21 #define PWM_ENABLE (1 << 0) 22 #define PWM_POLARITY (1 << 4) 23 24 #define PERIOD(x) (((x) * 0x10) + 0x10) 25 #define DUTY(x) (((x) * 0x10) + 0x14) 26 27 #define MIN_PERIOD 108 /* 9.2 MHz max. PWM clock */ 28 29 struct bcm2835_pwm { 30 struct pwm_chip chip; 31 struct device *dev; 32 unsigned long scaler; 33 void __iomem *base; 34 struct clk *clk; 35 }; 36 37 static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) 38 { 39 return container_of(chip, struct bcm2835_pwm, chip); 40 } 41 42 static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 43 { 44 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 45 u32 value; 46 47 value = readl(pc->base + PWM_CONTROL); 48 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); 49 value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm)); 50 writel(value, pc->base + PWM_CONTROL); 51 52 return 0; 53 } 54 55 static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 56 { 57 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 58 u32 value; 59 60 value = readl(pc->base + PWM_CONTROL); 61 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); 62 writel(value, pc->base + PWM_CONTROL); 63 } 64 65 static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 66 int duty_ns, int period_ns) 67 { 68 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 69 70 if (period_ns <= MIN_PERIOD) { 71 dev_err(pc->dev, "period %d not supported, minimum %d\n", 72 period_ns, MIN_PERIOD); 73 return -EINVAL; 74 } 75 76 writel(duty_ns / pc->scaler, pc->base + DUTY(pwm->hwpwm)); 77 writel(period_ns / pc->scaler, pc->base + PERIOD(pwm->hwpwm)); 78 79 return 0; 80 } 81 82 static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 83 { 84 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 85 u32 value; 86 87 value = readl(pc->base + PWM_CONTROL); 88 value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm); 89 writel(value, pc->base + PWM_CONTROL); 90 91 return 0; 92 } 93 94 static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 95 { 96 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 97 u32 value; 98 99 value = readl(pc->base + PWM_CONTROL); 100 value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm)); 101 writel(value, pc->base + PWM_CONTROL); 102 } 103 104 static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, 105 enum pwm_polarity polarity) 106 { 107 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 108 u32 value; 109 110 value = readl(pc->base + PWM_CONTROL); 111 112 if (polarity == PWM_POLARITY_NORMAL) 113 value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm)); 114 else 115 value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm); 116 117 writel(value, pc->base + PWM_CONTROL); 118 119 return 0; 120 } 121 122 static const struct pwm_ops bcm2835_pwm_ops = { 123 .request = bcm2835_pwm_request, 124 .free = bcm2835_pwm_free, 125 .config = bcm2835_pwm_config, 126 .enable = bcm2835_pwm_enable, 127 .disable = bcm2835_pwm_disable, 128 .set_polarity = bcm2835_set_polarity, 129 .owner = THIS_MODULE, 130 }; 131 132 static int bcm2835_pwm_probe(struct platform_device *pdev) 133 { 134 struct bcm2835_pwm *pc; 135 struct resource *res; 136 int ret; 137 138 pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); 139 if (!pc) 140 return -ENOMEM; 141 142 pc->dev = &pdev->dev; 143 144 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 145 pc->base = devm_ioremap_resource(&pdev->dev, res); 146 if (IS_ERR(pc->base)) 147 return PTR_ERR(pc->base); 148 149 pc->clk = devm_clk_get(&pdev->dev, NULL); 150 if (IS_ERR(pc->clk)) { 151 dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk)); 152 return PTR_ERR(pc->clk); 153 } 154 155 ret = clk_prepare_enable(pc->clk); 156 if (ret) 157 return ret; 158 159 pc->scaler = NSEC_PER_SEC / clk_get_rate(pc->clk); 160 161 pc->chip.dev = &pdev->dev; 162 pc->chip.ops = &bcm2835_pwm_ops; 163 pc->chip.npwm = 2; 164 165 platform_set_drvdata(pdev, pc); 166 167 ret = pwmchip_add(&pc->chip); 168 if (ret < 0) 169 goto add_fail; 170 171 return 0; 172 173 add_fail: 174 clk_disable_unprepare(pc->clk); 175 return ret; 176 } 177 178 static int bcm2835_pwm_remove(struct platform_device *pdev) 179 { 180 struct bcm2835_pwm *pc = platform_get_drvdata(pdev); 181 182 clk_disable_unprepare(pc->clk); 183 184 return pwmchip_remove(&pc->chip); 185 } 186 187 static const struct of_device_id bcm2835_pwm_of_match[] = { 188 { .compatible = "brcm,bcm2835-pwm", }, 189 { /* sentinel */ } 190 }; 191 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match); 192 193 static struct platform_driver bcm2835_pwm_driver = { 194 .driver = { 195 .name = "bcm2835-pwm", 196 .of_match_table = bcm2835_pwm_of_match, 197 }, 198 .probe = bcm2835_pwm_probe, 199 .remove = bcm2835_pwm_remove, 200 }; 201 module_platform_driver(bcm2835_pwm_driver); 202 203 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be"); 204 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver"); 205 MODULE_LICENSE("GPL v2"); 206