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 void __iomem *base; 33 struct clk *clk; 34 }; 35 to_bcm2835_pwm(struct pwm_chip * chip)36 static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) 37 { 38 return container_of(chip, struct bcm2835_pwm, chip); 39 } 40 bcm2835_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)41 static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 42 { 43 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 44 u32 value; 45 46 value = readl(pc->base + PWM_CONTROL); 47 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); 48 value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm)); 49 writel(value, pc->base + PWM_CONTROL); 50 51 return 0; 52 } 53 bcm2835_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)54 static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 55 { 56 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 57 u32 value; 58 59 value = readl(pc->base + PWM_CONTROL); 60 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); 61 writel(value, pc->base + PWM_CONTROL); 62 } 63 bcm2835_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)64 static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 65 int duty_ns, int period_ns) 66 { 67 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 68 unsigned long rate = clk_get_rate(pc->clk); 69 unsigned long scaler; 70 71 if (!rate) { 72 dev_err(pc->dev, "failed to get clock rate\n"); 73 return -EINVAL; 74 } 75 76 scaler = NSEC_PER_SEC / rate; 77 78 if (period_ns <= MIN_PERIOD) { 79 dev_err(pc->dev, "period %d not supported, minimum %d\n", 80 period_ns, MIN_PERIOD); 81 return -EINVAL; 82 } 83 84 writel(duty_ns / scaler, pc->base + DUTY(pwm->hwpwm)); 85 writel(period_ns / scaler, pc->base + PERIOD(pwm->hwpwm)); 86 87 return 0; 88 } 89 bcm2835_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)90 static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 91 { 92 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 93 u32 value; 94 95 value = readl(pc->base + PWM_CONTROL); 96 value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm); 97 writel(value, pc->base + PWM_CONTROL); 98 99 return 0; 100 } 101 bcm2835_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)102 static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 103 { 104 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 105 u32 value; 106 107 value = readl(pc->base + PWM_CONTROL); 108 value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm)); 109 writel(value, pc->base + PWM_CONTROL); 110 } 111 bcm2835_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)112 static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, 113 enum pwm_polarity polarity) 114 { 115 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 116 u32 value; 117 118 value = readl(pc->base + PWM_CONTROL); 119 120 if (polarity == PWM_POLARITY_NORMAL) 121 value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm)); 122 else 123 value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm); 124 125 writel(value, pc->base + PWM_CONTROL); 126 127 return 0; 128 } 129 130 static const struct pwm_ops bcm2835_pwm_ops = { 131 .request = bcm2835_pwm_request, 132 .free = bcm2835_pwm_free, 133 .config = bcm2835_pwm_config, 134 .enable = bcm2835_pwm_enable, 135 .disable = bcm2835_pwm_disable, 136 .set_polarity = bcm2835_set_polarity, 137 .owner = THIS_MODULE, 138 }; 139 bcm2835_pwm_probe(struct platform_device * pdev)140 static int bcm2835_pwm_probe(struct platform_device *pdev) 141 { 142 struct bcm2835_pwm *pc; 143 struct resource *res; 144 int ret; 145 146 pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); 147 if (!pc) 148 return -ENOMEM; 149 150 pc->dev = &pdev->dev; 151 152 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 153 pc->base = devm_ioremap_resource(&pdev->dev, res); 154 if (IS_ERR(pc->base)) 155 return PTR_ERR(pc->base); 156 157 pc->clk = devm_clk_get(&pdev->dev, NULL); 158 if (IS_ERR(pc->clk)) { 159 dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk)); 160 return PTR_ERR(pc->clk); 161 } 162 163 ret = clk_prepare_enable(pc->clk); 164 if (ret) 165 return ret; 166 167 pc->chip.dev = &pdev->dev; 168 pc->chip.ops = &bcm2835_pwm_ops; 169 pc->chip.npwm = 2; 170 pc->chip.of_xlate = of_pwm_xlate_with_flags; 171 pc->chip.of_pwm_n_cells = 3; 172 173 platform_set_drvdata(pdev, pc); 174 175 ret = pwmchip_add(&pc->chip); 176 if (ret < 0) 177 goto add_fail; 178 179 return 0; 180 181 add_fail: 182 clk_disable_unprepare(pc->clk); 183 return ret; 184 } 185 bcm2835_pwm_remove(struct platform_device * pdev)186 static int bcm2835_pwm_remove(struct platform_device *pdev) 187 { 188 struct bcm2835_pwm *pc = platform_get_drvdata(pdev); 189 190 clk_disable_unprepare(pc->clk); 191 192 return pwmchip_remove(&pc->chip); 193 } 194 195 static const struct of_device_id bcm2835_pwm_of_match[] = { 196 { .compatible = "brcm,bcm2835-pwm", }, 197 { /* sentinel */ } 198 }; 199 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match); 200 201 static struct platform_driver bcm2835_pwm_driver = { 202 .driver = { 203 .name = "bcm2835-pwm", 204 .of_match_table = bcm2835_pwm_of_match, 205 }, 206 .probe = bcm2835_pwm_probe, 207 .remove = bcm2835_pwm_remove, 208 }; 209 module_platform_driver(bcm2835_pwm_driver); 210 211 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>"); 212 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver"); 213 MODULE_LICENSE("GPL v2"); 214