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/mfd/cros_ec.h> 10 #include <linux/mfd/cros_ec_commands.h> 11 #include <linux/platform_device.h> 12 #include <linux/pwm.h> 13 #include <linux/slab.h> 14 15 /** 16 * struct cros_ec_pwm_device - Driver data for EC PWM 17 * 18 * @dev: Device node 19 * @ec: Pointer to EC device 20 * @chip: PWM controller chip 21 */ 22 struct cros_ec_pwm_device { 23 struct device *dev; 24 struct cros_ec_device *ec; 25 struct pwm_chip chip; 26 }; 27 28 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c) 29 { 30 return container_of(c, struct cros_ec_pwm_device, chip); 31 } 32 33 static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty) 34 { 35 struct { 36 struct cros_ec_command msg; 37 struct ec_params_pwm_set_duty params; 38 } __packed buf; 39 struct ec_params_pwm_set_duty *params = &buf.params; 40 struct cros_ec_command *msg = &buf.msg; 41 42 memset(&buf, 0, sizeof(buf)); 43 44 msg->version = 0; 45 msg->command = EC_CMD_PWM_SET_DUTY; 46 msg->insize = 0; 47 msg->outsize = sizeof(*params); 48 49 params->duty = duty; 50 params->pwm_type = EC_PWM_TYPE_GENERIC; 51 params->index = index; 52 53 return cros_ec_cmd_xfer_status(ec, msg); 54 } 55 56 static int __cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index, 57 u32 *result) 58 { 59 struct { 60 struct cros_ec_command msg; 61 union { 62 struct ec_params_pwm_get_duty params; 63 struct ec_response_pwm_get_duty resp; 64 }; 65 } __packed buf; 66 struct ec_params_pwm_get_duty *params = &buf.params; 67 struct ec_response_pwm_get_duty *resp = &buf.resp; 68 struct cros_ec_command *msg = &buf.msg; 69 int ret; 70 71 memset(&buf, 0, sizeof(buf)); 72 73 msg->version = 0; 74 msg->command = EC_CMD_PWM_GET_DUTY; 75 msg->insize = sizeof(*resp); 76 msg->outsize = sizeof(*params); 77 78 params->pwm_type = EC_PWM_TYPE_GENERIC; 79 params->index = index; 80 81 ret = cros_ec_cmd_xfer_status(ec, msg); 82 if (result) 83 *result = msg->result; 84 if (ret < 0) 85 return ret; 86 87 return resp->duty; 88 } 89 90 static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index) 91 { 92 return __cros_ec_pwm_get_duty(ec, index, NULL); 93 } 94 95 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 96 struct pwm_state *state) 97 { 98 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 99 int duty_cycle; 100 101 /* The EC won't let us change the period */ 102 if (state->period != EC_PWM_MAX_DUTY) 103 return -EINVAL; 104 105 /* 106 * EC doesn't separate the concept of duty cycle and enabled, but 107 * kernel does. Translate. 108 */ 109 duty_cycle = state->enabled ? state->duty_cycle : 0; 110 111 return cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle); 112 } 113 114 static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 115 struct pwm_state *state) 116 { 117 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 118 int ret; 119 120 ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm); 121 if (ret < 0) { 122 dev_err(chip->dev, "error getting initial duty: %d\n", ret); 123 return; 124 } 125 126 state->enabled = (ret > 0); 127 state->period = EC_PWM_MAX_DUTY; 128 129 /* Note that "disabled" and "duty cycle == 0" are treated the same */ 130 state->duty_cycle = ret; 131 } 132 133 static struct pwm_device * 134 cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) 135 { 136 struct pwm_device *pwm; 137 138 if (args->args[0] >= pc->npwm) 139 return ERR_PTR(-EINVAL); 140 141 pwm = pwm_request_from_chip(pc, args->args[0], NULL); 142 if (IS_ERR(pwm)) 143 return pwm; 144 145 /* The EC won't let us change the period */ 146 pwm->args.period = EC_PWM_MAX_DUTY; 147 148 return pwm; 149 } 150 151 static const struct pwm_ops cros_ec_pwm_ops = { 152 .get_state = cros_ec_pwm_get_state, 153 .apply = cros_ec_pwm_apply, 154 .owner = THIS_MODULE, 155 }; 156 157 static int cros_ec_num_pwms(struct cros_ec_device *ec) 158 { 159 int i, ret; 160 161 /* The index field is only 8 bits */ 162 for (i = 0; i <= U8_MAX; i++) { 163 u32 result = 0; 164 165 ret = __cros_ec_pwm_get_duty(ec, i, &result); 166 /* We want to parse EC protocol errors */ 167 if (ret < 0 && !(ret == -EPROTO && result)) 168 return ret; 169 170 /* 171 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM 172 * responses; everything else is treated as an error. 173 */ 174 if (result == EC_RES_INVALID_COMMAND) 175 return -ENODEV; 176 else if (result == EC_RES_INVALID_PARAM) 177 return i; 178 else if (result) 179 return -EPROTO; 180 } 181 182 return U8_MAX; 183 } 184 185 static int cros_ec_pwm_probe(struct platform_device *pdev) 186 { 187 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 188 struct device *dev = &pdev->dev; 189 struct cros_ec_pwm_device *ec_pwm; 190 struct pwm_chip *chip; 191 int ret; 192 193 if (!ec) { 194 dev_err(dev, "no parent EC device\n"); 195 return -EINVAL; 196 } 197 198 ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL); 199 if (!ec_pwm) 200 return -ENOMEM; 201 chip = &ec_pwm->chip; 202 ec_pwm->ec = ec; 203 204 /* PWM chip */ 205 chip->dev = dev; 206 chip->ops = &cros_ec_pwm_ops; 207 chip->of_xlate = cros_ec_pwm_xlate; 208 chip->of_pwm_n_cells = 1; 209 chip->base = -1; 210 ret = cros_ec_num_pwms(ec); 211 if (ret < 0) { 212 dev_err(dev, "Couldn't find PWMs: %d\n", ret); 213 return ret; 214 } 215 chip->npwm = ret; 216 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm); 217 218 ret = pwmchip_add(chip); 219 if (ret < 0) { 220 dev_err(dev, "cannot register PWM: %d\n", ret); 221 return ret; 222 } 223 224 platform_set_drvdata(pdev, ec_pwm); 225 226 return ret; 227 } 228 229 static int cros_ec_pwm_remove(struct platform_device *dev) 230 { 231 struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev); 232 struct pwm_chip *chip = &ec_pwm->chip; 233 234 return pwmchip_remove(chip); 235 } 236 237 #ifdef CONFIG_OF 238 static const struct of_device_id cros_ec_pwm_of_match[] = { 239 { .compatible = "google,cros-ec-pwm" }, 240 {}, 241 }; 242 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match); 243 #endif 244 245 static struct platform_driver cros_ec_pwm_driver = { 246 .probe = cros_ec_pwm_probe, 247 .remove = cros_ec_pwm_remove, 248 .driver = { 249 .name = "cros-ec-pwm", 250 .of_match_table = of_match_ptr(cros_ec_pwm_of_match), 251 }, 252 }; 253 module_platform_driver(cros_ec_pwm_driver); 254 255 MODULE_ALIAS("platform:cros-ec-pwm"); 256 MODULE_DESCRIPTION("ChromeOS EC PWM driver"); 257 MODULE_LICENSE("GPL v2"); 258