1 /* 2 * Marvell Berlin PWM driver 3 * 4 * Copyright (C) 2015 Marvell Technology Group Ltd. 5 * 6 * Author: Antoine Tenart <antoine.tenart@free-electrons.com> 7 * 8 * This file is licensed under the terms of the GNU General Public 9 * License version 2. This program is licensed "as is" without any 10 * warranty of any kind, whether express or implied. 11 */ 12 13 #include <linux/clk.h> 14 #include <linux/io.h> 15 #include <linux/kernel.h> 16 #include <linux/mod_devicetable.h> 17 #include <linux/module.h> 18 #include <linux/platform_device.h> 19 #include <linux/pwm.h> 20 #include <linux/slab.h> 21 22 #define BERLIN_PWM_EN 0x0 23 #define BERLIN_PWM_ENABLE BIT(0) 24 #define BERLIN_PWM_CONTROL 0x4 25 /* 26 * The prescaler claims to support 8 different moduli, configured using the 27 * low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64, 28 * 256, 1024, and 4096.) However, the moduli from 4 to 1024 appear to be 29 * implemented by internally shifting TCNT left without adding additional 30 * bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff; 31 * for 8, 0x1fff; and so on. This means that those moduli are entirely 32 * useless, as we could just do the shift ourselves. The 4096 modulus is 33 * implemented with a real prescaler, so we do use that, but we treat it 34 * as a flag instead of pretending the modulus is actually configurable. 35 */ 36 #define BERLIN_PWM_PRESCALE_4096 0x7 37 #define BERLIN_PWM_INVERT_POLARITY BIT(3) 38 #define BERLIN_PWM_DUTY 0x8 39 #define BERLIN_PWM_TCNT 0xc 40 #define BERLIN_PWM_MAX_TCNT 65535 41 42 #define BERLIN_PWM_NUMPWMS 4 43 44 struct berlin_pwm_channel { 45 u32 enable; 46 u32 ctrl; 47 u32 duty; 48 u32 tcnt; 49 }; 50 51 struct berlin_pwm_chip { 52 struct clk *clk; 53 void __iomem *base; 54 struct berlin_pwm_channel channel[BERLIN_PWM_NUMPWMS]; 55 }; 56 57 static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip) 58 { 59 return pwmchip_get_drvdata(chip); 60 } 61 62 static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *bpc, 63 unsigned int channel, unsigned long offset) 64 { 65 return readl_relaxed(bpc->base + channel * 0x10 + offset); 66 } 67 68 static inline void berlin_pwm_writel(struct berlin_pwm_chip *bpc, 69 unsigned int channel, u32 value, 70 unsigned long offset) 71 { 72 writel_relaxed(value, bpc->base + channel * 0x10 + offset); 73 } 74 75 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 76 u64 duty_ns, u64 period_ns) 77 { 78 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 79 bool prescale_4096 = false; 80 u32 value, duty, period; 81 u64 cycles; 82 83 cycles = clk_get_rate(bpc->clk); 84 cycles *= period_ns; 85 do_div(cycles, NSEC_PER_SEC); 86 87 if (cycles > BERLIN_PWM_MAX_TCNT) { 88 prescale_4096 = true; 89 cycles >>= 12; // Prescaled by 4096 90 91 if (cycles > BERLIN_PWM_MAX_TCNT) 92 return -ERANGE; 93 } 94 95 period = cycles; 96 cycles *= duty_ns; 97 do_div(cycles, period_ns); 98 duty = cycles; 99 100 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL); 101 if (prescale_4096) 102 value |= BERLIN_PWM_PRESCALE_4096; 103 else 104 value &= ~BERLIN_PWM_PRESCALE_4096; 105 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL); 106 107 berlin_pwm_writel(bpc, pwm->hwpwm, duty, BERLIN_PWM_DUTY); 108 berlin_pwm_writel(bpc, pwm->hwpwm, period, BERLIN_PWM_TCNT); 109 110 return 0; 111 } 112 113 static int berlin_pwm_set_polarity(struct pwm_chip *chip, 114 struct pwm_device *pwm, 115 enum pwm_polarity polarity) 116 { 117 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 118 u32 value; 119 120 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL); 121 122 if (polarity == PWM_POLARITY_NORMAL) 123 value &= ~BERLIN_PWM_INVERT_POLARITY; 124 else 125 value |= BERLIN_PWM_INVERT_POLARITY; 126 127 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL); 128 129 return 0; 130 } 131 132 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 133 { 134 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 135 u32 value; 136 137 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN); 138 value |= BERLIN_PWM_ENABLE; 139 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN); 140 141 return 0; 142 } 143 144 static void berlin_pwm_disable(struct pwm_chip *chip, 145 struct pwm_device *pwm) 146 { 147 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 148 u32 value; 149 150 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN); 151 value &= ~BERLIN_PWM_ENABLE; 152 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN); 153 } 154 155 static int berlin_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 156 const struct pwm_state *state) 157 { 158 int err; 159 bool enabled = pwm->state.enabled; 160 161 if (state->polarity != pwm->state.polarity) { 162 if (enabled) { 163 berlin_pwm_disable(chip, pwm); 164 enabled = false; 165 } 166 167 err = berlin_pwm_set_polarity(chip, pwm, state->polarity); 168 if (err) 169 return err; 170 } 171 172 if (!state->enabled) { 173 if (enabled) 174 berlin_pwm_disable(chip, pwm); 175 return 0; 176 } 177 178 err = berlin_pwm_config(chip, pwm, state->duty_cycle, state->period); 179 if (err) 180 return err; 181 182 if (!enabled) 183 return berlin_pwm_enable(chip, pwm); 184 185 return 0; 186 } 187 188 static const struct pwm_ops berlin_pwm_ops = { 189 .apply = berlin_pwm_apply, 190 }; 191 192 static const struct of_device_id berlin_pwm_match[] = { 193 { .compatible = "marvell,berlin-pwm" }, 194 { }, 195 }; 196 MODULE_DEVICE_TABLE(of, berlin_pwm_match); 197 198 static int berlin_pwm_probe(struct platform_device *pdev) 199 { 200 struct pwm_chip *chip; 201 struct berlin_pwm_chip *bpc; 202 int ret; 203 204 chip = devm_pwmchip_alloc(&pdev->dev, BERLIN_PWM_NUMPWMS, sizeof(*bpc)); 205 if (IS_ERR(chip)) 206 return PTR_ERR(chip); 207 bpc = to_berlin_pwm_chip(chip); 208 209 bpc->base = devm_platform_ioremap_resource(pdev, 0); 210 if (IS_ERR(bpc->base)) 211 return PTR_ERR(bpc->base); 212 213 bpc->clk = devm_clk_get_enabled(&pdev->dev, NULL); 214 if (IS_ERR(bpc->clk)) 215 return PTR_ERR(bpc->clk); 216 217 chip->ops = &berlin_pwm_ops; 218 219 ret = devm_pwmchip_add(&pdev->dev, chip); 220 if (ret < 0) 221 return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n"); 222 223 platform_set_drvdata(pdev, chip); 224 225 return 0; 226 } 227 228 static int berlin_pwm_suspend(struct device *dev) 229 { 230 struct pwm_chip *chip = dev_get_drvdata(dev); 231 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 232 unsigned int i; 233 234 for (i = 0; i < chip->npwm; i++) { 235 struct berlin_pwm_channel *channel = &bpc->channel[i]; 236 237 channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE); 238 channel->ctrl = berlin_pwm_readl(bpc, i, BERLIN_PWM_CONTROL); 239 channel->duty = berlin_pwm_readl(bpc, i, BERLIN_PWM_DUTY); 240 channel->tcnt = berlin_pwm_readl(bpc, i, BERLIN_PWM_TCNT); 241 } 242 243 clk_disable_unprepare(bpc->clk); 244 245 return 0; 246 } 247 248 static int berlin_pwm_resume(struct device *dev) 249 { 250 struct pwm_chip *chip = dev_get_drvdata(dev); 251 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 252 unsigned int i; 253 int ret; 254 255 ret = clk_prepare_enable(bpc->clk); 256 if (ret) 257 return ret; 258 259 for (i = 0; i < chip->npwm; i++) { 260 struct berlin_pwm_channel *channel = &bpc->channel[i]; 261 262 berlin_pwm_writel(bpc, i, channel->ctrl, BERLIN_PWM_CONTROL); 263 berlin_pwm_writel(bpc, i, channel->duty, BERLIN_PWM_DUTY); 264 berlin_pwm_writel(bpc, i, channel->tcnt, BERLIN_PWM_TCNT); 265 berlin_pwm_writel(bpc, i, channel->enable, BERLIN_PWM_ENABLE); 266 } 267 268 return 0; 269 } 270 271 static DEFINE_SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend, 272 berlin_pwm_resume); 273 274 static struct platform_driver berlin_pwm_driver = { 275 .probe = berlin_pwm_probe, 276 .driver = { 277 .name = "berlin-pwm", 278 .of_match_table = berlin_pwm_match, 279 .pm = pm_ptr(&berlin_pwm_pm_ops), 280 }, 281 }; 282 module_platform_driver(berlin_pwm_driver); 283 284 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>"); 285 MODULE_DESCRIPTION("Marvell Berlin PWM driver"); 286 MODULE_LICENSE("GPL v2"); 287