1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Expose a PWM controlled by the ChromeOS EC to the host processor. 4 * 5 * Copyright (C) 2016 Google, Inc. 6 */ 7 8 #include <linux/module.h> 9 #include <linux/of.h> 10 #include <linux/platform_data/cros_ec_commands.h> 11 #include <linux/platform_data/cros_ec_proto.h> 12 #include <linux/platform_device.h> 13 #include <linux/pwm.h> 14 #include <linux/slab.h> 15 16 #include <dt-bindings/mfd/cros_ec.h> 17 18 /** 19 * struct cros_ec_pwm_device - Driver data for EC PWM 20 * 21 * @ec: Pointer to EC device 22 * @chip: PWM controller chip 23 * @use_pwm_type: Use PWM types instead of generic channels 24 * @channel: array with per-channel data 25 */ 26 struct cros_ec_pwm_device { 27 struct cros_ec_device *ec; 28 struct pwm_chip chip; 29 bool use_pwm_type; 30 struct cros_ec_pwm *channel; 31 }; 32 33 /** 34 * struct cros_ec_pwm - per-PWM driver data 35 * @duty_cycle: cached duty cycle 36 */ 37 struct cros_ec_pwm { 38 u16 duty_cycle; 39 }; 40 41 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *chip) 42 { 43 return container_of(chip, struct cros_ec_pwm_device, chip); 44 } 45 46 static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type) 47 { 48 switch (dt_index) { 49 case CROS_EC_PWM_DT_KB_LIGHT: 50 *pwm_type = EC_PWM_TYPE_KB_LIGHT; 51 return 0; 52 case CROS_EC_PWM_DT_DISPLAY_LIGHT: 53 *pwm_type = EC_PWM_TYPE_DISPLAY_LIGHT; 54 return 0; 55 default: 56 return -EINVAL; 57 } 58 } 59 60 static int cros_ec_pwm_set_duty(struct cros_ec_pwm_device *ec_pwm, u8 index, 61 u16 duty) 62 { 63 struct cros_ec_device *ec = ec_pwm->ec; 64 struct { 65 struct cros_ec_command msg; 66 struct ec_params_pwm_set_duty params; 67 } __packed buf; 68 struct ec_params_pwm_set_duty *params = &buf.params; 69 struct cros_ec_command *msg = &buf.msg; 70 int ret; 71 72 memset(&buf, 0, sizeof(buf)); 73 74 msg->version = 0; 75 msg->command = EC_CMD_PWM_SET_DUTY; 76 msg->insize = 0; 77 msg->outsize = sizeof(*params); 78 79 params->duty = duty; 80 81 if (ec_pwm->use_pwm_type) { 82 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type); 83 if (ret) { 84 dev_err(ec->dev, "Invalid PWM type index: %d\n", index); 85 return ret; 86 } 87 params->index = 0; 88 } else { 89 params->pwm_type = EC_PWM_TYPE_GENERIC; 90 params->index = index; 91 } 92 93 return cros_ec_cmd_xfer_status(ec, msg); 94 } 95 96 static int cros_ec_pwm_get_duty(struct cros_ec_pwm_device *ec_pwm, u8 index) 97 { 98 struct cros_ec_device *ec = ec_pwm->ec; 99 struct { 100 struct cros_ec_command msg; 101 union { 102 struct ec_params_pwm_get_duty params; 103 struct ec_response_pwm_get_duty resp; 104 }; 105 } __packed buf; 106 struct ec_params_pwm_get_duty *params = &buf.params; 107 struct ec_response_pwm_get_duty *resp = &buf.resp; 108 struct cros_ec_command *msg = &buf.msg; 109 int ret; 110 111 memset(&buf, 0, sizeof(buf)); 112 113 msg->version = 0; 114 msg->command = EC_CMD_PWM_GET_DUTY; 115 msg->insize = sizeof(*resp); 116 msg->outsize = sizeof(*params); 117 118 if (ec_pwm->use_pwm_type) { 119 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type); 120 if (ret) { 121 dev_err(ec->dev, "Invalid PWM type index: %d\n", index); 122 return ret; 123 } 124 params->index = 0; 125 } else { 126 params->pwm_type = EC_PWM_TYPE_GENERIC; 127 params->index = index; 128 } 129 130 ret = cros_ec_cmd_xfer_status(ec, msg); 131 if (ret < 0) 132 return ret; 133 134 return resp->duty; 135 } 136 137 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 138 const struct pwm_state *state) 139 { 140 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 141 struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm]; 142 u16 duty_cycle; 143 int ret; 144 145 /* The EC won't let us change the period */ 146 if (state->period != EC_PWM_MAX_DUTY) 147 return -EINVAL; 148 149 if (state->polarity != PWM_POLARITY_NORMAL) 150 return -EINVAL; 151 152 /* 153 * EC doesn't separate the concept of duty cycle and enabled, but 154 * kernel does. Translate. 155 */ 156 duty_cycle = state->enabled ? state->duty_cycle : 0; 157 158 ret = cros_ec_pwm_set_duty(ec_pwm, pwm->hwpwm, duty_cycle); 159 if (ret < 0) 160 return ret; 161 162 channel->duty_cycle = state->duty_cycle; 163 164 return 0; 165 } 166 167 static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 168 struct pwm_state *state) 169 { 170 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 171 struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm]; 172 int ret; 173 174 ret = cros_ec_pwm_get_duty(ec_pwm, pwm->hwpwm); 175 if (ret < 0) { 176 dev_err(chip->dev, "error getting initial duty: %d\n", ret); 177 return ret; 178 } 179 180 state->enabled = (ret > 0); 181 state->period = EC_PWM_MAX_DUTY; 182 state->polarity = PWM_POLARITY_NORMAL; 183 184 /* 185 * Note that "disabled" and "duty cycle == 0" are treated the same. If 186 * the cached duty cycle is not zero, used the cached duty cycle. This 187 * ensures that the configured duty cycle is kept across a disable and 188 * enable operation and avoids potentially confusing consumers. 189 * 190 * For the case of the initial hardware readout, channel->duty_cycle 191 * will be 0 and the actual duty cycle read from the EC is used. 192 */ 193 if (ret == 0 && channel->duty_cycle > 0) 194 state->duty_cycle = channel->duty_cycle; 195 else 196 state->duty_cycle = ret; 197 198 return 0; 199 } 200 201 static struct pwm_device * 202 cros_ec_pwm_xlate(struct pwm_chip *chip, const struct of_phandle_args *args) 203 { 204 struct pwm_device *pwm; 205 206 if (args->args[0] >= chip->npwm) 207 return ERR_PTR(-EINVAL); 208 209 pwm = pwm_request_from_chip(chip, args->args[0], NULL); 210 if (IS_ERR(pwm)) 211 return pwm; 212 213 /* The EC won't let us change the period */ 214 pwm->args.period = EC_PWM_MAX_DUTY; 215 216 return pwm; 217 } 218 219 static const struct pwm_ops cros_ec_pwm_ops = { 220 .get_state = cros_ec_pwm_get_state, 221 .apply = cros_ec_pwm_apply, 222 }; 223 224 /* 225 * Determine the number of supported PWMs. The EC does not return the number 226 * of PWMs it supports directly, so we have to read the pwm duty cycle for 227 * subsequent channels until we get an error. 228 */ 229 static int cros_ec_num_pwms(struct cros_ec_pwm_device *ec_pwm) 230 { 231 int i, ret; 232 233 /* The index field is only 8 bits */ 234 for (i = 0; i <= U8_MAX; i++) { 235 ret = cros_ec_pwm_get_duty(ec_pwm, i); 236 /* 237 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM 238 * responses; everything else is treated as an error. 239 * The EC error codes map to -EOPNOTSUPP and -EINVAL, 240 * so check for those. 241 */ 242 switch (ret) { 243 case -EOPNOTSUPP: /* invalid command */ 244 return -ENODEV; 245 case -EINVAL: /* invalid parameter */ 246 return i; 247 default: 248 if (ret < 0) 249 return ret; 250 break; 251 } 252 } 253 254 return U8_MAX; 255 } 256 257 static int cros_ec_pwm_probe(struct platform_device *pdev) 258 { 259 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 260 struct device *dev = &pdev->dev; 261 struct device_node *np = pdev->dev.of_node; 262 struct cros_ec_pwm_device *ec_pwm; 263 struct pwm_chip *chip; 264 int ret; 265 266 if (!ec) 267 return dev_err_probe(dev, -EINVAL, "no parent EC device\n"); 268 269 ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL); 270 if (!ec_pwm) 271 return -ENOMEM; 272 chip = &ec_pwm->chip; 273 ec_pwm->ec = ec; 274 275 if (of_device_is_compatible(np, "google,cros-ec-pwm-type")) 276 ec_pwm->use_pwm_type = true; 277 278 /* PWM chip */ 279 chip->dev = dev; 280 chip->ops = &cros_ec_pwm_ops; 281 chip->of_xlate = cros_ec_pwm_xlate; 282 chip->of_pwm_n_cells = 1; 283 284 if (ec_pwm->use_pwm_type) { 285 chip->npwm = CROS_EC_PWM_DT_COUNT; 286 } else { 287 ret = cros_ec_num_pwms(ec_pwm); 288 if (ret < 0) 289 return dev_err_probe(dev, ret, "Couldn't find PWMs\n"); 290 chip->npwm = ret; 291 } 292 293 ec_pwm->channel = devm_kcalloc(dev, chip->npwm, sizeof(*ec_pwm->channel), 294 GFP_KERNEL); 295 if (!ec_pwm->channel) 296 return -ENOMEM; 297 298 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm); 299 300 ret = devm_pwmchip_add(dev, chip); 301 if (ret < 0) 302 return dev_err_probe(dev, ret, "cannot register PWM\n"); 303 304 return 0; 305 } 306 307 #ifdef CONFIG_OF 308 static const struct of_device_id cros_ec_pwm_of_match[] = { 309 { .compatible = "google,cros-ec-pwm" }, 310 { .compatible = "google,cros-ec-pwm-type" }, 311 {}, 312 }; 313 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match); 314 #endif 315 316 static struct platform_driver cros_ec_pwm_driver = { 317 .probe = cros_ec_pwm_probe, 318 .driver = { 319 .name = "cros-ec-pwm", 320 .of_match_table = of_match_ptr(cros_ec_pwm_of_match), 321 }, 322 }; 323 module_platform_driver(cros_ec_pwm_driver); 324 325 MODULE_ALIAS("platform:cros-ec-pwm"); 326 MODULE_DESCRIPTION("ChromeOS EC PWM driver"); 327 MODULE_LICENSE("GPL v2"); 328