1 // SPDX-License-Identifier: GPL-2.0 OR MIT 2 /* 3 * Driver for the Apple SoC PWM controller 4 * 5 * Copyright The Asahi Linux Contributors 6 * 7 * Limitations: 8 * - The writes to cycle registers are shadowed until a write to 9 * the control register. 10 * - If both OFF_CYCLES and ON_CYCLES are set to 0, the output 11 * is a constant off signal. 12 * - When APPLE_PWM_CTRL is set to 0, the output is constant low 13 */ 14 15 #include <linux/mod_devicetable.h> 16 #include <linux/module.h> 17 #include <linux/platform_device.h> 18 #include <linux/pwm.h> 19 #include <linux/io.h> 20 #include <linux/clk.h> 21 #include <linux/math64.h> 22 23 #define APPLE_PWM_CTRL 0x00 24 #define APPLE_PWM_ON_CYCLES 0x1c 25 #define APPLE_PWM_OFF_CYCLES 0x18 26 27 #define APPLE_PWM_CTRL_ENABLE BIT(0) 28 #define APPLE_PWM_CTRL_MODE BIT(2) 29 #define APPLE_PWM_CTRL_UPDATE BIT(5) 30 #define APPLE_PWM_CTRL_TRIGGER BIT(9) 31 #define APPLE_PWM_CTRL_INVERT BIT(10) 32 #define APPLE_PWM_CTRL_OUTPUT_ENABLE BIT(14) 33 34 struct apple_pwm { 35 void __iomem *base; 36 u64 clkrate; 37 }; 38 39 static inline struct apple_pwm *to_apple_pwm(struct pwm_chip *chip) 40 { 41 return pwmchip_get_drvdata(chip); 42 } 43 44 static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 45 const struct pwm_state *state) 46 { 47 struct apple_pwm *fpwm; 48 49 if (state->polarity == PWM_POLARITY_INVERSED) 50 return -EINVAL; 51 52 fpwm = to_apple_pwm(chip); 53 if (state->enabled) { 54 u64 on_cycles, off_cycles; 55 56 on_cycles = mul_u64_u64_div_u64(fpwm->clkrate, 57 state->duty_cycle, NSEC_PER_SEC); 58 if (on_cycles > 0xFFFFFFFF) 59 on_cycles = 0xFFFFFFFF; 60 61 off_cycles = mul_u64_u64_div_u64(fpwm->clkrate, 62 state->period, NSEC_PER_SEC) - on_cycles; 63 if (off_cycles > 0xFFFFFFFF) 64 off_cycles = 0xFFFFFFFF; 65 66 writel(on_cycles, fpwm->base + APPLE_PWM_ON_CYCLES); 67 writel(off_cycles, fpwm->base + APPLE_PWM_OFF_CYCLES); 68 writel(APPLE_PWM_CTRL_ENABLE | APPLE_PWM_CTRL_OUTPUT_ENABLE | APPLE_PWM_CTRL_UPDATE, 69 fpwm->base + APPLE_PWM_CTRL); 70 } else { 71 writel(0, fpwm->base + APPLE_PWM_CTRL); 72 } 73 return 0; 74 } 75 76 static int apple_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 77 struct pwm_state *state) 78 { 79 struct apple_pwm *fpwm; 80 u32 on_cycles, off_cycles, ctrl; 81 82 fpwm = to_apple_pwm(chip); 83 84 ctrl = readl(fpwm->base + APPLE_PWM_CTRL); 85 on_cycles = readl(fpwm->base + APPLE_PWM_ON_CYCLES); 86 off_cycles = readl(fpwm->base + APPLE_PWM_OFF_CYCLES); 87 88 state->enabled = (ctrl & APPLE_PWM_CTRL_ENABLE) && (ctrl & APPLE_PWM_CTRL_OUTPUT_ENABLE); 89 state->polarity = PWM_POLARITY_NORMAL; 90 // on_cycles + off_cycles is 33 bits, NSEC_PER_SEC is 30, there is no overflow 91 state->duty_cycle = DIV64_U64_ROUND_UP((u64)on_cycles * NSEC_PER_SEC, fpwm->clkrate); 92 state->period = DIV64_U64_ROUND_UP(((u64)off_cycles + (u64)on_cycles) * 93 NSEC_PER_SEC, fpwm->clkrate); 94 95 return 0; 96 } 97 98 static const struct pwm_ops apple_pwm_ops = { 99 .apply = apple_pwm_apply, 100 .get_state = apple_pwm_get_state, 101 }; 102 103 static int apple_pwm_probe(struct platform_device *pdev) 104 { 105 struct pwm_chip *chip; 106 struct apple_pwm *fpwm; 107 struct clk *clk; 108 int ret; 109 110 chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*fpwm)); 111 if (IS_ERR(chip)) 112 return PTR_ERR(chip); 113 114 fpwm = to_apple_pwm(chip); 115 116 fpwm->base = devm_platform_ioremap_resource(pdev, 0); 117 if (IS_ERR(fpwm->base)) 118 return PTR_ERR(fpwm->base); 119 120 clk = devm_clk_get_enabled(&pdev->dev, NULL); 121 if (IS_ERR(clk)) 122 return dev_err_probe(&pdev->dev, PTR_ERR(clk), "unable to get the clock"); 123 124 /* 125 * Uses the 24MHz system clock on all existing devices, can only 126 * happen if the device tree is broken 127 * 128 * This check is done to prevent an overflow in .apply 129 */ 130 fpwm->clkrate = clk_get_rate(clk); 131 if (fpwm->clkrate > NSEC_PER_SEC) 132 return dev_err_probe(&pdev->dev, -EINVAL, "pwm clock out of range"); 133 134 chip->ops = &apple_pwm_ops; 135 136 ret = devm_pwmchip_add(&pdev->dev, chip); 137 if (ret < 0) 138 return dev_err_probe(&pdev->dev, ret, "unable to add pwm chip"); 139 140 return 0; 141 } 142 143 static const struct of_device_id apple_pwm_of_match[] = { 144 { .compatible = "apple,s5l-fpwm" }, 145 {} 146 }; 147 MODULE_DEVICE_TABLE(of, apple_pwm_of_match); 148 149 static struct platform_driver apple_pwm_driver = { 150 .probe = apple_pwm_probe, 151 .driver = { 152 .name = "apple-pwm", 153 .of_match_table = apple_pwm_of_match, 154 }, 155 }; 156 module_platform_driver(apple_pwm_driver); 157 158 MODULE_DESCRIPTION("Apple SoC PWM driver"); 159 MODULE_LICENSE("Dual MIT/GPL"); 160