1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * PWM device driver for SUNPLUS SP7021 SoC 4 * 5 * Links: 6 * Reference Manual: 7 * https://sunplus-tibbo.atlassian.net/wiki/spaces/doc/overview 8 * 9 * Reference Manual(PWM module): 10 * https://sunplus.atlassian.net/wiki/spaces/doc/pages/461144198/12.+Pulse+Width+Modulation+PWM 11 * 12 * Limitations: 13 * - Only supports normal polarity. 14 * - It output low when PWM channel disabled. 15 * - When the parameters change, current running period will not be completed 16 * and run new settings immediately. 17 * - In .apply() PWM output need to write register FREQ and DUTY. When first write FREQ 18 * done and not yet write DUTY, it has short timing gap use new FREQ and old DUTY. 19 * 20 * Author: Hammer Hsieh <hammerh0314@gmail.com> 21 */ 22 #include <linux/bitfield.h> 23 #include <linux/clk.h> 24 #include <linux/io.h> 25 #include <linux/kernel.h> 26 #include <linux/mod_devicetable.h> 27 #include <linux/module.h> 28 #include <linux/platform_device.h> 29 #include <linux/pwm.h> 30 31 #define SP7021_PWM_MODE0 0x000 32 #define SP7021_PWM_MODE0_PWMEN(ch) BIT(ch) 33 #define SP7021_PWM_MODE0_BYPASS(ch) BIT(8 + (ch)) 34 #define SP7021_PWM_MODE1 0x004 35 #define SP7021_PWM_MODE1_CNT_EN(ch) BIT(ch) 36 #define SP7021_PWM_FREQ(ch) (0x008 + 4 * (ch)) 37 #define SP7021_PWM_FREQ_MAX GENMASK(15, 0) 38 #define SP7021_PWM_DUTY(ch) (0x018 + 4 * (ch)) 39 #define SP7021_PWM_DUTY_DD_SEL(ch) FIELD_PREP(GENMASK(9, 8), ch) 40 #define SP7021_PWM_DUTY_MAX GENMASK(7, 0) 41 #define SP7021_PWM_DUTY_MASK SP7021_PWM_DUTY_MAX 42 #define SP7021_PWM_FREQ_SCALER 256 43 #define SP7021_PWM_NUM 4 44 45 struct sunplus_pwm { 46 void __iomem *base; 47 struct clk *clk; 48 }; 49 50 static inline struct sunplus_pwm *to_sunplus_pwm(struct pwm_chip *chip) 51 { 52 return pwmchip_get_drvdata(chip); 53 } 54 55 static int sunplus_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 56 const struct pwm_state *state) 57 { 58 struct sunplus_pwm *priv = to_sunplus_pwm(chip); 59 u32 dd_freq, duty, mode0, mode1; 60 u64 clk_rate; 61 62 if (state->polarity != pwm->state.polarity) 63 return -EINVAL; 64 65 if (!state->enabled) { 66 /* disable pwm channel output */ 67 mode0 = readl(priv->base + SP7021_PWM_MODE0); 68 mode0 &= ~SP7021_PWM_MODE0_PWMEN(pwm->hwpwm); 69 writel(mode0, priv->base + SP7021_PWM_MODE0); 70 /* disable pwm channel clk source */ 71 mode1 = readl(priv->base + SP7021_PWM_MODE1); 72 mode1 &= ~SP7021_PWM_MODE1_CNT_EN(pwm->hwpwm); 73 writel(mode1, priv->base + SP7021_PWM_MODE1); 74 return 0; 75 } 76 77 clk_rate = clk_get_rate(priv->clk); 78 79 /* 80 * The following calculations might overflow if clk is bigger 81 * than 256 GHz. In practise it's 202.5MHz, so this limitation 82 * is only theoretic. 83 */ 84 if (clk_rate > (u64)SP7021_PWM_FREQ_SCALER * NSEC_PER_SEC) 85 return -EINVAL; 86 87 /* 88 * With clk_rate limited above we have dd_freq <= state->period, 89 * so this cannot overflow. 90 */ 91 dd_freq = mul_u64_u64_div_u64(clk_rate, state->period, (u64)SP7021_PWM_FREQ_SCALER 92 * NSEC_PER_SEC); 93 94 if (dd_freq == 0) 95 return -EINVAL; 96 97 if (dd_freq > SP7021_PWM_FREQ_MAX) 98 dd_freq = SP7021_PWM_FREQ_MAX; 99 100 writel(dd_freq, priv->base + SP7021_PWM_FREQ(pwm->hwpwm)); 101 102 /* cal and set pwm duty */ 103 mode0 = readl(priv->base + SP7021_PWM_MODE0); 104 mode0 |= SP7021_PWM_MODE0_PWMEN(pwm->hwpwm); 105 mode1 = readl(priv->base + SP7021_PWM_MODE1); 106 mode1 |= SP7021_PWM_MODE1_CNT_EN(pwm->hwpwm); 107 if (state->duty_cycle == state->period) { 108 /* PWM channel output = high */ 109 mode0 |= SP7021_PWM_MODE0_BYPASS(pwm->hwpwm); 110 duty = SP7021_PWM_DUTY_DD_SEL(pwm->hwpwm) | SP7021_PWM_DUTY_MAX; 111 } else { 112 mode0 &= ~SP7021_PWM_MODE0_BYPASS(pwm->hwpwm); 113 /* 114 * duty_ns <= period_ns 27 bits, clk_rate 28 bits, won't overflow. 115 */ 116 duty = mul_u64_u64_div_u64(state->duty_cycle, clk_rate, 117 (u64)dd_freq * NSEC_PER_SEC); 118 duty = SP7021_PWM_DUTY_DD_SEL(pwm->hwpwm) | duty; 119 } 120 writel(duty, priv->base + SP7021_PWM_DUTY(pwm->hwpwm)); 121 writel(mode1, priv->base + SP7021_PWM_MODE1); 122 writel(mode0, priv->base + SP7021_PWM_MODE0); 123 124 return 0; 125 } 126 127 static int sunplus_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 128 struct pwm_state *state) 129 { 130 struct sunplus_pwm *priv = to_sunplus_pwm(chip); 131 u32 mode0, dd_freq, duty; 132 u64 clk_rate; 133 134 mode0 = readl(priv->base + SP7021_PWM_MODE0); 135 136 if (mode0 & BIT(pwm->hwpwm)) { 137 clk_rate = clk_get_rate(priv->clk); 138 dd_freq = readl(priv->base + SP7021_PWM_FREQ(pwm->hwpwm)); 139 duty = readl(priv->base + SP7021_PWM_DUTY(pwm->hwpwm)); 140 duty = FIELD_GET(SP7021_PWM_DUTY_MASK, duty); 141 /* 142 * dd_freq 16 bits, SP7021_PWM_FREQ_SCALER 8 bits 143 * NSEC_PER_SEC 30 bits, won't overflow. 144 */ 145 state->period = DIV64_U64_ROUND_UP((u64)dd_freq * (u64)SP7021_PWM_FREQ_SCALER 146 * NSEC_PER_SEC, clk_rate); 147 /* 148 * dd_freq 16 bits, duty 8 bits, NSEC_PER_SEC 30 bits, won't overflow. 149 */ 150 state->duty_cycle = DIV64_U64_ROUND_UP((u64)dd_freq * (u64)duty * NSEC_PER_SEC, 151 clk_rate); 152 state->enabled = true; 153 } else { 154 state->enabled = false; 155 } 156 157 state->polarity = PWM_POLARITY_NORMAL; 158 159 return 0; 160 } 161 162 static const struct pwm_ops sunplus_pwm_ops = { 163 .apply = sunplus_pwm_apply, 164 .get_state = sunplus_pwm_get_state, 165 }; 166 167 static void sunplus_pwm_clk_release(void *data) 168 { 169 struct clk *clk = data; 170 171 clk_disable_unprepare(clk); 172 } 173 174 static int sunplus_pwm_probe(struct platform_device *pdev) 175 { 176 struct device *dev = &pdev->dev; 177 struct pwm_chip *chip; 178 struct sunplus_pwm *priv; 179 int ret; 180 181 chip = devm_pwmchip_alloc(dev, SP7021_PWM_NUM, sizeof(*priv)); 182 if (IS_ERR(chip)) 183 return PTR_ERR(chip); 184 priv = to_sunplus_pwm(chip); 185 186 priv->base = devm_platform_ioremap_resource(pdev, 0); 187 if (IS_ERR(priv->base)) 188 return PTR_ERR(priv->base); 189 190 priv->clk = devm_clk_get(dev, NULL); 191 if (IS_ERR(priv->clk)) 192 return dev_err_probe(dev, PTR_ERR(priv->clk), 193 "get pwm clock failed\n"); 194 195 ret = clk_prepare_enable(priv->clk); 196 if (ret < 0) { 197 dev_err(dev, "failed to enable clock: %d\n", ret); 198 return ret; 199 } 200 201 ret = devm_add_action_or_reset(dev, sunplus_pwm_clk_release, priv->clk); 202 if (ret < 0) { 203 dev_err(dev, "failed to release clock: %d\n", ret); 204 return ret; 205 } 206 207 chip->ops = &sunplus_pwm_ops; 208 209 ret = devm_pwmchip_add(dev, chip); 210 if (ret < 0) 211 return dev_err_probe(dev, ret, "Cannot register sunplus PWM\n"); 212 213 return 0; 214 } 215 216 static const struct of_device_id sunplus_pwm_of_match[] = { 217 { .compatible = "sunplus,sp7021-pwm", }, 218 {} 219 }; 220 MODULE_DEVICE_TABLE(of, sunplus_pwm_of_match); 221 222 static struct platform_driver sunplus_pwm_driver = { 223 .probe = sunplus_pwm_probe, 224 .driver = { 225 .name = "sunplus-pwm", 226 .of_match_table = sunplus_pwm_of_match, 227 }, 228 }; 229 module_platform_driver(sunplus_pwm_driver); 230 231 MODULE_DESCRIPTION("Sunplus SoC PWM Driver"); 232 MODULE_AUTHOR("Hammer Hsieh <hammerh0314@gmail.com>"); 233 MODULE_LICENSE("GPL"); 234