1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* NXP PCF50633 ADC Driver 3 * 4 * (C) 2006-2008 by Openmoko, Inc. 5 * Author: Balaji Rao <balajirrao@openmoko.org> 6 * All rights reserved. 7 * 8 * Broken down from monstrous PCF50633 driver mainly by 9 * Harald Welte, Andy Green and Werner Almesberger 10 * 11 * NOTE: This driver does not yet support subtractive ADC mode, which means 12 * you can do only one measurement per read request. 13 */ 14 15 #include <linux/kernel.h> 16 #include <linux/slab.h> 17 #include <linux/module.h> 18 #include <linux/device.h> 19 #include <linux/platform_device.h> 20 #include <linux/completion.h> 21 22 #include <linux/mfd/pcf50633/core.h> 23 #include <linux/mfd/pcf50633/adc.h> 24 25 struct pcf50633_adc_request { 26 int mux; 27 int avg; 28 void (*callback)(struct pcf50633 *, void *, int); 29 void *callback_param; 30 }; 31 32 struct pcf50633_adc_sync_request { 33 int result; 34 struct completion completion; 35 }; 36 37 #define PCF50633_MAX_ADC_FIFO_DEPTH 8 38 39 struct pcf50633_adc { 40 struct pcf50633 *pcf; 41 42 /* Private stuff */ 43 struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH]; 44 int queue_head; 45 int queue_tail; 46 struct mutex queue_mutex; 47 }; 48 49 static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf) 50 { 51 return platform_get_drvdata(pcf->adc_pdev); 52 } 53 54 static void adc_setup(struct pcf50633 *pcf, int channel, int avg) 55 { 56 channel &= PCF50633_ADCC1_ADCMUX_MASK; 57 58 /* kill ratiometric, but enable ACCSW biasing */ 59 pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00); 60 pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01); 61 62 /* start ADC conversion on selected channel */ 63 pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg | 64 PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT); 65 } 66 67 static void trigger_next_adc_job_if_any(struct pcf50633 *pcf) 68 { 69 struct pcf50633_adc *adc = __to_adc(pcf); 70 int head; 71 72 head = adc->queue_head; 73 74 if (!adc->queue[head]) 75 return; 76 77 adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg); 78 } 79 80 static int 81 adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req) 82 { 83 struct pcf50633_adc *adc = __to_adc(pcf); 84 int head, tail; 85 86 mutex_lock(&adc->queue_mutex); 87 88 head = adc->queue_head; 89 tail = adc->queue_tail; 90 91 if (adc->queue[tail]) { 92 mutex_unlock(&adc->queue_mutex); 93 dev_err(pcf->dev, "ADC queue is full, dropping request\n"); 94 return -EBUSY; 95 } 96 97 adc->queue[tail] = req; 98 if (head == tail) 99 trigger_next_adc_job_if_any(pcf); 100 adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1); 101 102 mutex_unlock(&adc->queue_mutex); 103 104 return 0; 105 } 106 107 static void pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param, 108 int result) 109 { 110 struct pcf50633_adc_sync_request *req = param; 111 112 req->result = result; 113 complete(&req->completion); 114 } 115 116 int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg) 117 { 118 struct pcf50633_adc_sync_request req; 119 int ret; 120 121 init_completion(&req.completion); 122 123 ret = pcf50633_adc_async_read(pcf, mux, avg, 124 pcf50633_adc_sync_read_callback, &req); 125 if (ret) 126 return ret; 127 128 wait_for_completion(&req.completion); 129 130 return req.result; 131 } 132 EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read); 133 134 int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg, 135 void (*callback)(struct pcf50633 *, void *, int), 136 void *callback_param) 137 { 138 struct pcf50633_adc_request *req; 139 int ret; 140 141 /* req is freed when the result is ready, in interrupt handler */ 142 req = kmalloc(sizeof(*req), GFP_KERNEL); 143 if (!req) 144 return -ENOMEM; 145 146 req->mux = mux; 147 req->avg = avg; 148 req->callback = callback; 149 req->callback_param = callback_param; 150 151 ret = adc_enqueue_request(pcf, req); 152 if (ret) 153 kfree(req); 154 155 return ret; 156 } 157 EXPORT_SYMBOL_GPL(pcf50633_adc_async_read); 158 159 static int adc_result(struct pcf50633 *pcf) 160 { 161 u8 adcs1, adcs3; 162 u16 result; 163 164 adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1); 165 adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3); 166 result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK); 167 168 dev_dbg(pcf->dev, "adc result = %d\n", result); 169 170 return result; 171 } 172 173 static void pcf50633_adc_irq(int irq, void *data) 174 { 175 struct pcf50633_adc *adc = data; 176 struct pcf50633 *pcf = adc->pcf; 177 struct pcf50633_adc_request *req; 178 int head, res; 179 180 mutex_lock(&adc->queue_mutex); 181 head = adc->queue_head; 182 183 req = adc->queue[head]; 184 if (WARN_ON(!req)) { 185 dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n"); 186 mutex_unlock(&adc->queue_mutex); 187 return; 188 } 189 adc->queue[head] = NULL; 190 adc->queue_head = (head + 1) & 191 (PCF50633_MAX_ADC_FIFO_DEPTH - 1); 192 193 res = adc_result(pcf); 194 trigger_next_adc_job_if_any(pcf); 195 196 mutex_unlock(&adc->queue_mutex); 197 198 req->callback(pcf, req->callback_param, res); 199 kfree(req); 200 } 201 202 static int pcf50633_adc_probe(struct platform_device *pdev) 203 { 204 struct pcf50633_adc *adc; 205 206 adc = devm_kzalloc(&pdev->dev, sizeof(*adc), GFP_KERNEL); 207 if (!adc) 208 return -ENOMEM; 209 210 adc->pcf = dev_to_pcf50633(pdev->dev.parent); 211 platform_set_drvdata(pdev, adc); 212 213 pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY, 214 pcf50633_adc_irq, adc); 215 216 mutex_init(&adc->queue_mutex); 217 218 return 0; 219 } 220 221 static int pcf50633_adc_remove(struct platform_device *pdev) 222 { 223 struct pcf50633_adc *adc = platform_get_drvdata(pdev); 224 int i, head; 225 226 pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY); 227 228 mutex_lock(&adc->queue_mutex); 229 head = adc->queue_head; 230 231 if (WARN_ON(adc->queue[head])) 232 dev_err(adc->pcf->dev, 233 "adc driver removed with request pending\n"); 234 235 for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++) 236 kfree(adc->queue[i]); 237 238 mutex_unlock(&adc->queue_mutex); 239 240 return 0; 241 } 242 243 static struct platform_driver pcf50633_adc_driver = { 244 .driver = { 245 .name = "pcf50633-adc", 246 }, 247 .probe = pcf50633_adc_probe, 248 .remove = pcf50633_adc_remove, 249 }; 250 251 module_platform_driver(pcf50633_adc_driver); 252 253 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>"); 254 MODULE_DESCRIPTION("PCF50633 adc driver"); 255 MODULE_LICENSE("GPL"); 256 MODULE_ALIAS("platform:pcf50633-adc"); 257 258