1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Toshiba Visconti pulse-width-modulation controller driver 4 * 5 * Copyright (c) 2020 - 2021 TOSHIBA CORPORATION 6 * Copyright (c) 2020 - 2021 Toshiba Electronic Devices & Storage Corporation 7 * 8 * Authors: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> 9 * 10 * Limitations: 11 * - The fixed input clock is running at 1 MHz and is divided by either 1, 12 * 2, 4 or 8. 13 * - When the settings of the PWM are modified, the new values are shadowed 14 * in hardware until the PIPGM_PCSR register is written and the currently 15 * running period is completed. This way the hardware switches atomically 16 * from the old setting to the new. 17 * - Disabling the hardware completes the currently running period and keeps 18 * the output at low level at all times. 19 */ 20 21 #include <linux/err.h> 22 #include <linux/io.h> 23 #include <linux/module.h> 24 #include <linux/of.h> 25 #include <linux/platform_device.h> 26 #include <linux/pwm.h> 27 28 #define PIPGM_PCSR(ch) (0x400 + 4 * (ch)) 29 #define PIPGM_PDUT(ch) (0x420 + 4 * (ch)) 30 #define PIPGM_PWMC(ch) (0x440 + 4 * (ch)) 31 32 #define PIPGM_PWMC_PWMACT BIT(5) 33 #define PIPGM_PWMC_CLK_MASK GENMASK(1, 0) 34 #define PIPGM_PWMC_POLARITY_MASK GENMASK(5, 5) 35 36 struct visconti_pwm_chip { 37 void __iomem *base; 38 }; 39 40 static inline struct visconti_pwm_chip *visconti_pwm_from_chip(struct pwm_chip *chip) 41 { 42 return pwmchip_get_drvdata(chip); 43 } 44 45 static int visconti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 46 const struct pwm_state *state) 47 { 48 struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip); 49 u32 period, duty_cycle, pwmc0; 50 51 if (!state->enabled) { 52 writel(0, priv->base + PIPGM_PCSR(pwm->hwpwm)); 53 return 0; 54 } 55 56 /* 57 * The biggest period the hardware can provide is 58 * (0xffff << 3) * 1000 ns 59 * This value fits easily in an u32, so simplify the maths by 60 * capping the values to 32 bit integers. 61 */ 62 if (state->period > (0xffff << 3) * 1000) 63 period = (0xffff << 3) * 1000; 64 else 65 period = state->period; 66 67 if (state->duty_cycle > period) 68 duty_cycle = period; 69 else 70 duty_cycle = state->duty_cycle; 71 72 /* 73 * The input clock runs fixed at 1 MHz, so we have only 74 * microsecond resolution and so can divide by 75 * NSEC_PER_SEC / CLKFREQ = 1000 without losing precision. 76 */ 77 period /= 1000; 78 duty_cycle /= 1000; 79 80 if (!period) 81 return -ERANGE; 82 83 /* 84 * PWMC controls a divider that divides the input clk by a power of two 85 * between 1 and 8. As a smaller divider yields higher precision, pick 86 * the smallest possible one. As period is at most 0xffff << 3, pwmc0 is 87 * in the intended range [0..3]. 88 */ 89 pwmc0 = fls(period >> 16); 90 if (WARN_ON(pwmc0 > 3)) 91 return -EINVAL; 92 93 period >>= pwmc0; 94 duty_cycle >>= pwmc0; 95 96 if (state->polarity == PWM_POLARITY_INVERSED) 97 pwmc0 |= PIPGM_PWMC_PWMACT; 98 writel(pwmc0, priv->base + PIPGM_PWMC(pwm->hwpwm)); 99 writel(duty_cycle, priv->base + PIPGM_PDUT(pwm->hwpwm)); 100 writel(period, priv->base + PIPGM_PCSR(pwm->hwpwm)); 101 102 return 0; 103 } 104 105 static int visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 106 struct pwm_state *state) 107 { 108 struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip); 109 u32 period, duty, pwmc0, pwmc0_clk; 110 111 period = readl(priv->base + PIPGM_PCSR(pwm->hwpwm)); 112 duty = readl(priv->base + PIPGM_PDUT(pwm->hwpwm)); 113 pwmc0 = readl(priv->base + PIPGM_PWMC(pwm->hwpwm)); 114 pwmc0_clk = pwmc0 & PIPGM_PWMC_CLK_MASK; 115 116 state->period = (period << pwmc0_clk) * NSEC_PER_USEC; 117 state->duty_cycle = (duty << pwmc0_clk) * NSEC_PER_USEC; 118 if (pwmc0 & PIPGM_PWMC_POLARITY_MASK) 119 state->polarity = PWM_POLARITY_INVERSED; 120 else 121 state->polarity = PWM_POLARITY_NORMAL; 122 123 state->enabled = true; 124 125 return 0; 126 } 127 128 static const struct pwm_ops visconti_pwm_ops = { 129 .apply = visconti_pwm_apply, 130 .get_state = visconti_pwm_get_state, 131 }; 132 133 static int visconti_pwm_probe(struct platform_device *pdev) 134 { 135 struct device *dev = &pdev->dev; 136 struct pwm_chip *chip; 137 struct visconti_pwm_chip *priv; 138 int ret; 139 140 chip = devm_pwmchip_alloc(dev, 4, sizeof(*priv)); 141 if (IS_ERR(chip)) 142 return PTR_ERR(chip); 143 priv = visconti_pwm_from_chip(chip); 144 145 priv->base = devm_platform_ioremap_resource(pdev, 0); 146 if (IS_ERR(priv->base)) 147 return PTR_ERR(priv->base); 148 149 chip->ops = &visconti_pwm_ops; 150 151 ret = devm_pwmchip_add(&pdev->dev, chip); 152 if (ret < 0) 153 return dev_err_probe(&pdev->dev, ret, "Cannot register visconti PWM\n"); 154 155 return 0; 156 } 157 158 static const struct of_device_id visconti_pwm_of_match[] = { 159 { .compatible = "toshiba,visconti-pwm", }, 160 { } 161 }; 162 MODULE_DEVICE_TABLE(of, visconti_pwm_of_match); 163 164 static struct platform_driver visconti_pwm_driver = { 165 .driver = { 166 .name = "pwm-visconti", 167 .of_match_table = visconti_pwm_of_match, 168 }, 169 .probe = visconti_pwm_probe, 170 }; 171 module_platform_driver(visconti_pwm_driver); 172 173 MODULE_DESCRIPTION("Toshiba Visconti Pulse Width Modulator driver"); 174 MODULE_LICENSE("GPL v2"); 175 MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>"); 176 MODULE_ALIAS("platform:pwm-visconti"); 177