1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be> 4 */ 5 6 #include <linux/clk.h> 7 #include <linux/err.h> 8 #include <linux/io.h> 9 #include <linux/module.h> 10 #include <linux/of.h> 11 #include <linux/platform_device.h> 12 #include <linux/pwm.h> 13 14 #define PWM_CONTROL 0x000 15 #define PWM_CONTROL_SHIFT(x) ((x) * 8) 16 #define PWM_CONTROL_MASK 0xff 17 #define PWM_MODE 0x80 /* set timer in PWM mode */ 18 #define PWM_ENABLE (1 << 0) 19 #define PWM_POLARITY (1 << 4) 20 21 #define PERIOD(x) (((x) * 0x10) + 0x10) 22 #define DUTY(x) (((x) * 0x10) + 0x14) 23 24 #define PERIOD_MIN 0x2 25 26 struct bcm2835_pwm { 27 void __iomem *base; 28 struct clk *clk; 29 unsigned long rate; 30 }; 31 32 static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) 33 { 34 return pwmchip_get_drvdata(chip); 35 } 36 37 static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 38 { 39 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 40 u32 value; 41 42 value = readl(pc->base + PWM_CONTROL); 43 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); 44 value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm)); 45 writel(value, pc->base + PWM_CONTROL); 46 47 return 0; 48 } 49 50 static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 51 { 52 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 53 u32 value; 54 55 value = readl(pc->base + PWM_CONTROL); 56 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); 57 writel(value, pc->base + PWM_CONTROL); 58 } 59 60 static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 61 const struct pwm_state *state) 62 { 63 64 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); 65 unsigned long long period_cycles; 66 u64 max_period; 67 68 u32 val; 69 70 /* 71 * period_cycles must be a 32 bit value, so period * rate / NSEC_PER_SEC 72 * must be <= U32_MAX. As U32_MAX * NSEC_PER_SEC < U64_MAX the 73 * multiplication period * rate doesn't overflow. 74 * To calculate the maximal possible period that guarantees the 75 * above inequality: 76 * 77 * round(period * rate / NSEC_PER_SEC) <= U32_MAX 78 * <=> period * rate / NSEC_PER_SEC < U32_MAX + 0.5 79 * <=> period * rate < (U32_MAX + 0.5) * NSEC_PER_SEC 80 * <=> period < ((U32_MAX + 0.5) * NSEC_PER_SEC) / rate 81 * <=> period < ((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate 82 * <=> period <= ceil((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate) - 1 83 */ 84 max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, pc->rate) - 1; 85 86 if (state->period > max_period) 87 return -EINVAL; 88 89 /* set period */ 90 period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * pc->rate, NSEC_PER_SEC); 91 92 /* don't accept a period that is too small */ 93 if (period_cycles < PERIOD_MIN) 94 return -EINVAL; 95 96 writel(period_cycles, pc->base + PERIOD(pwm->hwpwm)); 97 98 /* set duty cycle */ 99 val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * pc->rate, NSEC_PER_SEC); 100 writel(val, pc->base + DUTY(pwm->hwpwm)); 101 102 /* set polarity */ 103 val = readl(pc->base + PWM_CONTROL); 104 105 if (state->polarity == PWM_POLARITY_NORMAL) 106 val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm)); 107 else 108 val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm); 109 110 /* enable/disable */ 111 if (state->enabled) 112 val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm); 113 else 114 val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm)); 115 116 writel(val, pc->base + PWM_CONTROL); 117 118 return 0; 119 } 120 121 static const struct pwm_ops bcm2835_pwm_ops = { 122 .request = bcm2835_pwm_request, 123 .free = bcm2835_pwm_free, 124 .apply = bcm2835_pwm_apply, 125 }; 126 127 static void devm_clk_rate_exclusive_put(void *data) 128 { 129 struct clk *clk = data; 130 131 clk_rate_exclusive_put(clk); 132 } 133 134 static int bcm2835_pwm_probe(struct platform_device *pdev) 135 { 136 struct pwm_chip *chip; 137 struct bcm2835_pwm *pc; 138 int ret; 139 140 chip = devm_pwmchip_alloc(&pdev->dev, 2, sizeof(*pc)); 141 if (IS_ERR(chip)) 142 return PTR_ERR(chip); 143 pc = to_bcm2835_pwm(chip); 144 145 pc->base = devm_platform_ioremap_resource(pdev, 0); 146 if (IS_ERR(pc->base)) 147 return PTR_ERR(pc->base); 148 149 pc->clk = devm_clk_get_enabled(&pdev->dev, NULL); 150 if (IS_ERR(pc->clk)) 151 return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk), 152 "clock not found\n"); 153 154 ret = clk_rate_exclusive_get(pc->clk); 155 if (ret) 156 return dev_err_probe(&pdev->dev, ret, 157 "fail to get exclusive rate\n"); 158 159 ret = devm_add_action_or_reset(&pdev->dev, devm_clk_rate_exclusive_put, 160 pc->clk); 161 if (ret) 162 return ret; 163 164 pc->rate = clk_get_rate(pc->clk); 165 if (!pc->rate) 166 return dev_err_probe(&pdev->dev, -EINVAL, 167 "failed to get clock rate\n"); 168 169 chip->ops = &bcm2835_pwm_ops; 170 chip->atomic = true; 171 172 platform_set_drvdata(pdev, pc); 173 174 ret = devm_pwmchip_add(&pdev->dev, chip); 175 if (ret < 0) 176 return dev_err_probe(&pdev->dev, ret, 177 "failed to add pwmchip\n"); 178 179 return 0; 180 } 181 182 static int bcm2835_pwm_suspend(struct device *dev) 183 { 184 struct bcm2835_pwm *pc = dev_get_drvdata(dev); 185 186 clk_disable_unprepare(pc->clk); 187 188 return 0; 189 } 190 191 static int bcm2835_pwm_resume(struct device *dev) 192 { 193 struct bcm2835_pwm *pc = dev_get_drvdata(dev); 194 195 return clk_prepare_enable(pc->clk); 196 } 197 198 static DEFINE_SIMPLE_DEV_PM_OPS(bcm2835_pwm_pm_ops, bcm2835_pwm_suspend, 199 bcm2835_pwm_resume); 200 201 static const struct of_device_id bcm2835_pwm_of_match[] = { 202 { .compatible = "brcm,bcm2835-pwm", }, 203 { /* sentinel */ } 204 }; 205 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match); 206 207 static struct platform_driver bcm2835_pwm_driver = { 208 .driver = { 209 .name = "bcm2835-pwm", 210 .of_match_table = bcm2835_pwm_of_match, 211 .pm = pm_ptr(&bcm2835_pwm_pm_ops), 212 }, 213 .probe = bcm2835_pwm_probe, 214 }; 215 module_platform_driver(bcm2835_pwm_driver); 216 217 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>"); 218 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver"); 219 MODULE_LICENSE("GPL v2"); 220