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 *chip, 60 unsigned int channel, unsigned long offset) 61 { 62 return readl_relaxed(chip->base + channel * 0x10 + offset); 63 } 64 65 static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip, 66 unsigned int channel, u32 value, 67 unsigned long offset) 68 { 69 writel_relaxed(value, chip->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 pwm_set_chip_data(pwm, NULL); 88 kfree(channel); 89 } 90 91 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev, 92 int duty_ns, int period_ns) 93 { 94 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 95 bool prescale_4096 = false; 96 u32 value, duty, period; 97 u64 cycles; 98 99 cycles = clk_get_rate(pwm->clk); 100 cycles *= period_ns; 101 do_div(cycles, NSEC_PER_SEC); 102 103 if (cycles > BERLIN_PWM_MAX_TCNT) { 104 prescale_4096 = true; 105 cycles >>= 12; // Prescaled by 4096 106 107 if (cycles > BERLIN_PWM_MAX_TCNT) 108 return -ERANGE; 109 } 110 111 period = cycles; 112 cycles *= duty_ns; 113 do_div(cycles, period_ns); 114 duty = cycles; 115 116 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL); 117 if (prescale_4096) 118 value |= BERLIN_PWM_PRESCALE_4096; 119 else 120 value &= ~BERLIN_PWM_PRESCALE_4096; 121 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL); 122 123 berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY); 124 berlin_pwm_writel(pwm, pwm_dev->hwpwm, period, BERLIN_PWM_TCNT); 125 126 return 0; 127 } 128 129 static int berlin_pwm_set_polarity(struct pwm_chip *chip, 130 struct pwm_device *pwm_dev, 131 enum pwm_polarity polarity) 132 { 133 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 134 u32 value; 135 136 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL); 137 138 if (polarity == PWM_POLARITY_NORMAL) 139 value &= ~BERLIN_PWM_INVERT_POLARITY; 140 else 141 value |= BERLIN_PWM_INVERT_POLARITY; 142 143 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL); 144 145 return 0; 146 } 147 148 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev) 149 { 150 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 151 u32 value; 152 153 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN); 154 value |= BERLIN_PWM_ENABLE; 155 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN); 156 157 return 0; 158 } 159 160 static void berlin_pwm_disable(struct pwm_chip *chip, 161 struct pwm_device *pwm_dev) 162 { 163 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 164 u32 value; 165 166 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN); 167 value &= ~BERLIN_PWM_ENABLE; 168 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN); 169 } 170 171 static const struct pwm_ops berlin_pwm_ops = { 172 .request = berlin_pwm_request, 173 .free = berlin_pwm_free, 174 .config = berlin_pwm_config, 175 .set_polarity = berlin_pwm_set_polarity, 176 .enable = berlin_pwm_enable, 177 .disable = berlin_pwm_disable, 178 .owner = THIS_MODULE, 179 }; 180 181 static const struct of_device_id berlin_pwm_match[] = { 182 { .compatible = "marvell,berlin-pwm" }, 183 { }, 184 }; 185 MODULE_DEVICE_TABLE(of, berlin_pwm_match); 186 187 static int berlin_pwm_probe(struct platform_device *pdev) 188 { 189 struct berlin_pwm_chip *pwm; 190 struct resource *res; 191 int ret; 192 193 pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); 194 if (!pwm) 195 return -ENOMEM; 196 197 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 198 pwm->base = devm_ioremap_resource(&pdev->dev, res); 199 if (IS_ERR(pwm->base)) 200 return PTR_ERR(pwm->base); 201 202 pwm->clk = devm_clk_get(&pdev->dev, NULL); 203 if (IS_ERR(pwm->clk)) 204 return PTR_ERR(pwm->clk); 205 206 ret = clk_prepare_enable(pwm->clk); 207 if (ret) 208 return ret; 209 210 pwm->chip.dev = &pdev->dev; 211 pwm->chip.ops = &berlin_pwm_ops; 212 pwm->chip.base = -1; 213 pwm->chip.npwm = 4; 214 pwm->chip.of_xlate = of_pwm_xlate_with_flags; 215 pwm->chip.of_pwm_n_cells = 3; 216 217 ret = pwmchip_add(&pwm->chip); 218 if (ret < 0) { 219 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); 220 clk_disable_unprepare(pwm->clk); 221 return ret; 222 } 223 224 platform_set_drvdata(pdev, pwm); 225 226 return 0; 227 } 228 229 static int berlin_pwm_remove(struct platform_device *pdev) 230 { 231 struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev); 232 int ret; 233 234 ret = pwmchip_remove(&pwm->chip); 235 clk_disable_unprepare(pwm->clk); 236 237 return ret; 238 } 239 240 #ifdef CONFIG_PM_SLEEP 241 static int berlin_pwm_suspend(struct device *dev) 242 { 243 struct berlin_pwm_chip *pwm = dev_get_drvdata(dev); 244 unsigned int i; 245 246 for (i = 0; i < pwm->chip.npwm; i++) { 247 struct berlin_pwm_channel *channel; 248 249 channel = pwm_get_chip_data(&pwm->chip.pwms[i]); 250 if (!channel) 251 continue; 252 253 channel->enable = berlin_pwm_readl(pwm, i, BERLIN_PWM_ENABLE); 254 channel->ctrl = berlin_pwm_readl(pwm, i, BERLIN_PWM_CONTROL); 255 channel->duty = berlin_pwm_readl(pwm, i, BERLIN_PWM_DUTY); 256 channel->tcnt = berlin_pwm_readl(pwm, i, BERLIN_PWM_TCNT); 257 } 258 259 clk_disable_unprepare(pwm->clk); 260 261 return 0; 262 } 263 264 static int berlin_pwm_resume(struct device *dev) 265 { 266 struct berlin_pwm_chip *pwm = dev_get_drvdata(dev); 267 unsigned int i; 268 int ret; 269 270 ret = clk_prepare_enable(pwm->clk); 271 if (ret) 272 return ret; 273 274 for (i = 0; i < pwm->chip.npwm; i++) { 275 struct berlin_pwm_channel *channel; 276 277 channel = pwm_get_chip_data(&pwm->chip.pwms[i]); 278 if (!channel) 279 continue; 280 281 berlin_pwm_writel(pwm, i, channel->ctrl, BERLIN_PWM_CONTROL); 282 berlin_pwm_writel(pwm, i, channel->duty, BERLIN_PWM_DUTY); 283 berlin_pwm_writel(pwm, i, channel->tcnt, BERLIN_PWM_TCNT); 284 berlin_pwm_writel(pwm, i, channel->enable, BERLIN_PWM_ENABLE); 285 } 286 287 return 0; 288 } 289 #endif 290 291 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend, 292 berlin_pwm_resume); 293 294 static struct platform_driver berlin_pwm_driver = { 295 .probe = berlin_pwm_probe, 296 .remove = berlin_pwm_remove, 297 .driver = { 298 .name = "berlin-pwm", 299 .of_match_table = berlin_pwm_match, 300 .pm = &berlin_pwm_pm_ops, 301 }, 302 }; 303 module_platform_driver(berlin_pwm_driver); 304 305 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>"); 306 MODULE_DESCRIPTION("Marvell Berlin PWM driver"); 307 MODULE_LICENSE("GPL v2"); 308