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/module.h> 17 #include <linux/platform_device.h> 18 #include <linux/pwm.h> 19 #include <linux/slab.h> 20 21 #define BERLIN_PWM_EN 0x0 22 #define BERLIN_PWM_ENABLE BIT(0) 23 #define BERLIN_PWM_CONTROL 0x4 24 /* 25 * The prescaler claims to support 8 different moduli, configured using the 26 * low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64, 27 * 256, 1024, and 4096.) However, the moduli from 4 to 1024 appear to be 28 * implemented by internally shifting TCNT left without adding additional 29 * bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff; 30 * for 8, 0x1fff; and so on. This means that those moduli are entirely 31 * useless, as we could just do the shift ourselves. The 4096 modulus is 32 * implemented with a real prescaler, so we do use that, but we treat it 33 * as a flag instead of pretending the modulus is actually configurable. 34 */ 35 #define BERLIN_PWM_PRESCALE_4096 0x7 36 #define BERLIN_PWM_INVERT_POLARITY BIT(3) 37 #define BERLIN_PWM_DUTY 0x8 38 #define BERLIN_PWM_TCNT 0xc 39 #define BERLIN_PWM_MAX_TCNT 65535 40 41 struct berlin_pwm_channel { 42 u32 enable; 43 u32 ctrl; 44 u32 duty; 45 u32 tcnt; 46 }; 47 48 struct berlin_pwm_chip { 49 struct pwm_chip chip; 50 struct clk *clk; 51 void __iomem *base; 52 }; 53 54 static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip) 55 { 56 return container_of(chip, struct berlin_pwm_chip, chip); 57 } 58 59 static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *bpc, 60 unsigned int channel, unsigned long offset) 61 { 62 return readl_relaxed(bpc->base + channel * 0x10 + offset); 63 } 64 65 static inline void berlin_pwm_writel(struct berlin_pwm_chip *bpc, 66 unsigned int channel, u32 value, 67 unsigned long offset) 68 { 69 writel_relaxed(value, bpc->base + channel * 0x10 + offset); 70 } 71 72 static int berlin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 73 { 74 struct berlin_pwm_channel *channel; 75 76 channel = kzalloc(sizeof(*channel), GFP_KERNEL); 77 if (!channel) 78 return -ENOMEM; 79 80 return pwm_set_chip_data(pwm, channel); 81 } 82 83 static void berlin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 84 { 85 struct berlin_pwm_channel *channel = pwm_get_chip_data(pwm); 86 87 kfree(channel); 88 } 89 90 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 91 u64 duty_ns, u64 period_ns) 92 { 93 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 94 bool prescale_4096 = false; 95 u32 value, duty, period; 96 u64 cycles; 97 98 cycles = clk_get_rate(bpc->clk); 99 cycles *= period_ns; 100 do_div(cycles, NSEC_PER_SEC); 101 102 if (cycles > BERLIN_PWM_MAX_TCNT) { 103 prescale_4096 = true; 104 cycles >>= 12; // Prescaled by 4096 105 106 if (cycles > BERLIN_PWM_MAX_TCNT) 107 return -ERANGE; 108 } 109 110 period = cycles; 111 cycles *= duty_ns; 112 do_div(cycles, period_ns); 113 duty = cycles; 114 115 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL); 116 if (prescale_4096) 117 value |= BERLIN_PWM_PRESCALE_4096; 118 else 119 value &= ~BERLIN_PWM_PRESCALE_4096; 120 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL); 121 122 berlin_pwm_writel(bpc, pwm->hwpwm, duty, BERLIN_PWM_DUTY); 123 berlin_pwm_writel(bpc, pwm->hwpwm, period, BERLIN_PWM_TCNT); 124 125 return 0; 126 } 127 128 static int berlin_pwm_set_polarity(struct pwm_chip *chip, 129 struct pwm_device *pwm, 130 enum pwm_polarity polarity) 131 { 132 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 133 u32 value; 134 135 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL); 136 137 if (polarity == PWM_POLARITY_NORMAL) 138 value &= ~BERLIN_PWM_INVERT_POLARITY; 139 else 140 value |= BERLIN_PWM_INVERT_POLARITY; 141 142 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL); 143 144 return 0; 145 } 146 147 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 148 { 149 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 150 u32 value; 151 152 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN); 153 value |= BERLIN_PWM_ENABLE; 154 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN); 155 156 return 0; 157 } 158 159 static void berlin_pwm_disable(struct pwm_chip *chip, 160 struct pwm_device *pwm) 161 { 162 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip); 163 u32 value; 164 165 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN); 166 value &= ~BERLIN_PWM_ENABLE; 167 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN); 168 } 169 170 static int berlin_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 171 const struct pwm_state *state) 172 { 173 int err; 174 bool enabled = pwm->state.enabled; 175 176 if (state->polarity != pwm->state.polarity) { 177 if (enabled) { 178 berlin_pwm_disable(chip, pwm); 179 enabled = false; 180 } 181 182 err = berlin_pwm_set_polarity(chip, pwm, state->polarity); 183 if (err) 184 return err; 185 } 186 187 if (!state->enabled) { 188 if (enabled) 189 berlin_pwm_disable(chip, pwm); 190 return 0; 191 } 192 193 if (state->period != pwm->state.period || 194 state->duty_cycle != pwm->state.duty_cycle) { 195 err = berlin_pwm_config(chip, pwm, state->duty_cycle, state->period); 196 if (err) 197 return err; 198 } 199 200 if (!enabled) 201 return berlin_pwm_enable(chip, pwm); 202 203 return 0; 204 } 205 206 static const struct pwm_ops berlin_pwm_ops = { 207 .request = berlin_pwm_request, 208 .free = berlin_pwm_free, 209 .apply = berlin_pwm_apply, 210 .owner = THIS_MODULE, 211 }; 212 213 static const struct of_device_id berlin_pwm_match[] = { 214 { .compatible = "marvell,berlin-pwm" }, 215 { }, 216 }; 217 MODULE_DEVICE_TABLE(of, berlin_pwm_match); 218 219 static int berlin_pwm_probe(struct platform_device *pdev) 220 { 221 struct berlin_pwm_chip *bpc; 222 int ret; 223 224 bpc = devm_kzalloc(&pdev->dev, sizeof(*bpc), GFP_KERNEL); 225 if (!bpc) 226 return -ENOMEM; 227 228 bpc->base = devm_platform_ioremap_resource(pdev, 0); 229 if (IS_ERR(bpc->base)) 230 return PTR_ERR(bpc->base); 231 232 bpc->clk = devm_clk_get(&pdev->dev, NULL); 233 if (IS_ERR(bpc->clk)) 234 return PTR_ERR(bpc->clk); 235 236 ret = clk_prepare_enable(bpc->clk); 237 if (ret) 238 return ret; 239 240 bpc->chip.dev = &pdev->dev; 241 bpc->chip.ops = &berlin_pwm_ops; 242 bpc->chip.npwm = 4; 243 244 ret = pwmchip_add(&bpc->chip); 245 if (ret < 0) { 246 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); 247 clk_disable_unprepare(bpc->clk); 248 return ret; 249 } 250 251 platform_set_drvdata(pdev, bpc); 252 253 return 0; 254 } 255 256 static int berlin_pwm_remove(struct platform_device *pdev) 257 { 258 struct berlin_pwm_chip *bpc = platform_get_drvdata(pdev); 259 260 pwmchip_remove(&bpc->chip); 261 262 clk_disable_unprepare(bpc->clk); 263 264 return 0; 265 } 266 267 #ifdef CONFIG_PM_SLEEP 268 static int berlin_pwm_suspend(struct device *dev) 269 { 270 struct berlin_pwm_chip *bpc = dev_get_drvdata(dev); 271 unsigned int i; 272 273 for (i = 0; i < bpc->chip.npwm; i++) { 274 struct berlin_pwm_channel *channel; 275 276 channel = pwm_get_chip_data(&bpc->chip.pwms[i]); 277 if (!channel) 278 continue; 279 280 channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE); 281 channel->ctrl = berlin_pwm_readl(bpc, i, BERLIN_PWM_CONTROL); 282 channel->duty = berlin_pwm_readl(bpc, i, BERLIN_PWM_DUTY); 283 channel->tcnt = berlin_pwm_readl(bpc, i, BERLIN_PWM_TCNT); 284 } 285 286 clk_disable_unprepare(bpc->clk); 287 288 return 0; 289 } 290 291 static int berlin_pwm_resume(struct device *dev) 292 { 293 struct berlin_pwm_chip *bpc = dev_get_drvdata(dev); 294 unsigned int i; 295 int ret; 296 297 ret = clk_prepare_enable(bpc->clk); 298 if (ret) 299 return ret; 300 301 for (i = 0; i < bpc->chip.npwm; i++) { 302 struct berlin_pwm_channel *channel; 303 304 channel = pwm_get_chip_data(&bpc->chip.pwms[i]); 305 if (!channel) 306 continue; 307 308 berlin_pwm_writel(bpc, i, channel->ctrl, BERLIN_PWM_CONTROL); 309 berlin_pwm_writel(bpc, i, channel->duty, BERLIN_PWM_DUTY); 310 berlin_pwm_writel(bpc, i, channel->tcnt, BERLIN_PWM_TCNT); 311 berlin_pwm_writel(bpc, i, channel->enable, BERLIN_PWM_ENABLE); 312 } 313 314 return 0; 315 } 316 #endif 317 318 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend, 319 berlin_pwm_resume); 320 321 static struct platform_driver berlin_pwm_driver = { 322 .probe = berlin_pwm_probe, 323 .remove = berlin_pwm_remove, 324 .driver = { 325 .name = "berlin-pwm", 326 .of_match_table = berlin_pwm_match, 327 .pm = &berlin_pwm_pm_ops, 328 }, 329 }; 330 module_platform_driver(berlin_pwm_driver); 331 332 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>"); 333 MODULE_DESCRIPTION("Marvell Berlin PWM driver"); 334 MODULE_LICENSE("GPL v2"); 335