1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * lpc32xx_adc.c - Support for ADC in LPC32XX 4 * 5 * 3-channel, 10-bit ADC 6 * 7 * Copyright (C) 2011, 2012 Roland Stigge <stigge@antcom.de> 8 */ 9 10 #include <linux/clk.h> 11 #include <linux/completion.h> 12 #include <linux/err.h> 13 #include <linux/iio/iio.h> 14 #include <linux/interrupt.h> 15 #include <linux/io.h> 16 #include <linux/module.h> 17 #include <linux/mod_devicetable.h> 18 #include <linux/mutex.h> 19 #include <linux/platform_device.h> 20 #include <linux/regulator/consumer.h> 21 22 /* 23 * LPC32XX registers definitions 24 */ 25 #define LPC32XXAD_SELECT(x) ((x) + 0x04) 26 #define LPC32XXAD_CTRL(x) ((x) + 0x08) 27 #define LPC32XXAD_VALUE(x) ((x) + 0x48) 28 29 /* Bit definitions for LPC32XXAD_SELECT: */ 30 /* constant, always write this value! */ 31 #define LPC32XXAD_REFm 0x00000200 32 /* constant, always write this value! */ 33 #define LPC32XXAD_REFp 0x00000080 34 /* multiple of this is the channel number: 0, 1, 2 */ 35 #define LPC32XXAD_IN 0x00000010 36 /* constant, always write this value! */ 37 #define LPC32XXAD_INTERNAL 0x00000004 38 39 /* Bit definitions for LPC32XXAD_CTRL: */ 40 #define LPC32XXAD_STROBE 0x00000002 41 #define LPC32XXAD_PDN_CTRL 0x00000004 42 43 /* Bit definitions for LPC32XXAD_VALUE: */ 44 #define LPC32XXAD_VALUE_MASK 0x000003FF 45 46 #define LPC32XXAD_NAME "lpc32xx-adc" 47 48 struct lpc32xx_adc_state { 49 void __iomem *adc_base; 50 struct clk *clk; 51 struct completion completion; 52 struct regulator *vref; 53 /* lock to protect against multiple access to the device */ 54 struct mutex lock; 55 56 u32 value; 57 }; 58 59 static int lpc32xx_read_raw(struct iio_dev *indio_dev, 60 struct iio_chan_spec const *chan, 61 int *val, 62 int *val2, 63 long mask) 64 { 65 struct lpc32xx_adc_state *st = iio_priv(indio_dev); 66 int ret; 67 68 switch (mask) { 69 case IIO_CHAN_INFO_RAW: 70 mutex_lock(&st->lock); 71 ret = clk_prepare_enable(st->clk); 72 if (ret) { 73 mutex_unlock(&st->lock); 74 return ret; 75 } 76 /* Measurement setup */ 77 __raw_writel(LPC32XXAD_INTERNAL | (chan->address) | 78 LPC32XXAD_REFp | LPC32XXAD_REFm, 79 LPC32XXAD_SELECT(st->adc_base)); 80 /* Trigger conversion */ 81 __raw_writel(LPC32XXAD_PDN_CTRL | LPC32XXAD_STROBE, 82 LPC32XXAD_CTRL(st->adc_base)); 83 wait_for_completion(&st->completion); /* set by ISR */ 84 clk_disable_unprepare(st->clk); 85 *val = st->value; 86 mutex_unlock(&st->lock); 87 88 return IIO_VAL_INT; 89 90 case IIO_CHAN_INFO_SCALE: 91 *val = regulator_get_voltage(st->vref) / 1000; 92 *val2 = 10; 93 94 return IIO_VAL_FRACTIONAL_LOG2; 95 default: 96 return -EINVAL; 97 } 98 } 99 100 static const struct iio_info lpc32xx_adc_iio_info = { 101 .read_raw = &lpc32xx_read_raw, 102 }; 103 104 #define LPC32XX_ADC_CHANNEL_BASE(_index) \ 105 .type = IIO_VOLTAGE, \ 106 .indexed = 1, \ 107 .channel = _index, \ 108 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 109 .address = LPC32XXAD_IN * _index, \ 110 .scan_index = _index, 111 112 #define LPC32XX_ADC_CHANNEL(_index) { \ 113 LPC32XX_ADC_CHANNEL_BASE(_index) \ 114 } 115 116 #define LPC32XX_ADC_SCALE_CHANNEL(_index) { \ 117 LPC32XX_ADC_CHANNEL_BASE(_index) \ 118 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \ 119 } 120 121 static const struct iio_chan_spec lpc32xx_adc_iio_channels[] = { 122 LPC32XX_ADC_CHANNEL(0), 123 LPC32XX_ADC_CHANNEL(1), 124 LPC32XX_ADC_CHANNEL(2), 125 }; 126 127 static const struct iio_chan_spec lpc32xx_adc_iio_scale_channels[] = { 128 LPC32XX_ADC_SCALE_CHANNEL(0), 129 LPC32XX_ADC_SCALE_CHANNEL(1), 130 LPC32XX_ADC_SCALE_CHANNEL(2), 131 }; 132 133 static irqreturn_t lpc32xx_adc_isr(int irq, void *dev_id) 134 { 135 struct lpc32xx_adc_state *st = dev_id; 136 137 /* Read value and clear irq */ 138 st->value = __raw_readl(LPC32XXAD_VALUE(st->adc_base)) & 139 LPC32XXAD_VALUE_MASK; 140 complete(&st->completion); 141 142 return IRQ_HANDLED; 143 } 144 145 static int lpc32xx_adc_probe(struct platform_device *pdev) 146 { 147 struct lpc32xx_adc_state *st = NULL; 148 struct resource *res; 149 int retval = -ENODEV; 150 struct iio_dev *iodev = NULL; 151 int irq; 152 153 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 154 if (!res) { 155 dev_err(&pdev->dev, "failed to get platform I/O memory\n"); 156 return -ENXIO; 157 } 158 159 iodev = devm_iio_device_alloc(&pdev->dev, sizeof(*st)); 160 if (!iodev) 161 return -ENOMEM; 162 163 st = iio_priv(iodev); 164 165 st->adc_base = devm_ioremap(&pdev->dev, res->start, 166 resource_size(res)); 167 if (!st->adc_base) { 168 dev_err(&pdev->dev, "failed mapping memory\n"); 169 return -EBUSY; 170 } 171 172 st->clk = devm_clk_get(&pdev->dev, NULL); 173 if (IS_ERR(st->clk)) { 174 dev_err(&pdev->dev, "failed getting clock\n"); 175 return PTR_ERR(st->clk); 176 } 177 178 irq = platform_get_irq(pdev, 0); 179 if (irq < 0) 180 return irq; 181 182 retval = devm_request_irq(&pdev->dev, irq, lpc32xx_adc_isr, 0, 183 LPC32XXAD_NAME, st); 184 if (retval < 0) { 185 dev_err(&pdev->dev, "failed requesting interrupt\n"); 186 return retval; 187 } 188 189 st->vref = devm_regulator_get(&pdev->dev, "vref"); 190 if (IS_ERR(st->vref)) { 191 iodev->channels = lpc32xx_adc_iio_channels; 192 dev_info(&pdev->dev, 193 "Missing vref regulator: No scaling available\n"); 194 } else { 195 iodev->channels = lpc32xx_adc_iio_scale_channels; 196 } 197 198 platform_set_drvdata(pdev, iodev); 199 200 init_completion(&st->completion); 201 202 iodev->name = LPC32XXAD_NAME; 203 iodev->info = &lpc32xx_adc_iio_info; 204 iodev->modes = INDIO_DIRECT_MODE; 205 iodev->num_channels = ARRAY_SIZE(lpc32xx_adc_iio_channels); 206 207 mutex_init(&st->lock); 208 209 retval = devm_iio_device_register(&pdev->dev, iodev); 210 if (retval) 211 return retval; 212 213 dev_info(&pdev->dev, "LPC32XX ADC driver loaded, IRQ %d\n", irq); 214 215 return 0; 216 } 217 218 static const struct of_device_id lpc32xx_adc_match[] = { 219 { .compatible = "nxp,lpc3220-adc" }, 220 {}, 221 }; 222 MODULE_DEVICE_TABLE(of, lpc32xx_adc_match); 223 224 static struct platform_driver lpc32xx_adc_driver = { 225 .probe = lpc32xx_adc_probe, 226 .driver = { 227 .name = LPC32XXAD_NAME, 228 .of_match_table = lpc32xx_adc_match, 229 }, 230 }; 231 232 module_platform_driver(lpc32xx_adc_driver); 233 234 MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>"); 235 MODULE_DESCRIPTION("LPC32XX ADC driver"); 236 MODULE_LICENSE("GPL"); 237