1 /* NXP PCF50633 ADC Driver 2 * 3 * (C) 2006-2008 by Openmoko, Inc. 4 * Author: Balaji Rao <balajirrao@openmoko.org> 5 * All rights reserved. 6 * 7 * Broken down from monstrous PCF50633 driver mainly by 8 * Harald Welte, Andy Green and Werner Almesberger 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License as published by the 12 * Free Software Foundation; either version 2 of the License, or (at your 13 * option) any later version. 14 * 15 * NOTE: This driver does not yet support subtractive ADC mode, which means 16 * you can do only one measurement per read request. 17 */ 18 19 #include <linux/kernel.h> 20 #include <linux/slab.h> 21 #include <linux/module.h> 22 #include <linux/init.h> 23 #include <linux/device.h> 24 #include <linux/platform_device.h> 25 #include <linux/completion.h> 26 27 #include <linux/mfd/pcf50633/core.h> 28 #include <linux/mfd/pcf50633/adc.h> 29 30 struct pcf50633_adc_request { 31 int mux; 32 int avg; 33 void (*callback)(struct pcf50633 *, void *, int); 34 void *callback_param; 35 }; 36 37 struct pcf50633_adc_sync_request { 38 int result; 39 struct completion completion; 40 }; 41 42 #define PCF50633_MAX_ADC_FIFO_DEPTH 8 43 44 struct pcf50633_adc { 45 struct pcf50633 *pcf; 46 47 /* Private stuff */ 48 struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH]; 49 int queue_head; 50 int queue_tail; 51 struct mutex queue_mutex; 52 }; 53 54 static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf) 55 { 56 return platform_get_drvdata(pcf->adc_pdev); 57 } 58 59 static void adc_setup(struct pcf50633 *pcf, int channel, int avg) 60 { 61 channel &= PCF50633_ADCC1_ADCMUX_MASK; 62 63 /* kill ratiometric, but enable ACCSW biasing */ 64 pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00); 65 pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01); 66 67 /* start ADC conversion on selected channel */ 68 pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg | 69 PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT); 70 } 71 72 static void trigger_next_adc_job_if_any(struct pcf50633 *pcf) 73 { 74 struct pcf50633_adc *adc = __to_adc(pcf); 75 int head; 76 77 head = adc->queue_head; 78 79 if (!adc->queue[head]) 80 return; 81 82 adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg); 83 } 84 85 static int 86 adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req) 87 { 88 struct pcf50633_adc *adc = __to_adc(pcf); 89 int head, tail; 90 91 mutex_lock(&adc->queue_mutex); 92 93 head = adc->queue_head; 94 tail = adc->queue_tail; 95 96 if (adc->queue[tail]) { 97 mutex_unlock(&adc->queue_mutex); 98 dev_err(pcf->dev, "ADC queue is full, dropping request\n"); 99 return -EBUSY; 100 } 101 102 adc->queue[tail] = req; 103 if (head == tail) 104 trigger_next_adc_job_if_any(pcf); 105 adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1); 106 107 mutex_unlock(&adc->queue_mutex); 108 109 return 0; 110 } 111 112 static void pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param, 113 int result) 114 { 115 struct pcf50633_adc_sync_request *req = param; 116 117 req->result = result; 118 complete(&req->completion); 119 } 120 121 int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg) 122 { 123 struct pcf50633_adc_sync_request req; 124 int ret; 125 126 init_completion(&req.completion); 127 128 ret = pcf50633_adc_async_read(pcf, mux, avg, 129 pcf50633_adc_sync_read_callback, &req); 130 if (ret) 131 return ret; 132 133 wait_for_completion(&req.completion); 134 135 return req.result; 136 } 137 EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read); 138 139 int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg, 140 void (*callback)(struct pcf50633 *, void *, int), 141 void *callback_param) 142 { 143 struct pcf50633_adc_request *req; 144 145 /* req is freed when the result is ready, in interrupt handler */ 146 req = kmalloc(sizeof(*req), GFP_KERNEL); 147 if (!req) 148 return -ENOMEM; 149 150 req->mux = mux; 151 req->avg = avg; 152 req->callback = callback; 153 req->callback_param = callback_param; 154 155 return adc_enqueue_request(pcf, req); 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