1 /* 2 * lpc32xx_adc.c - Support for ADC in LPC32XX 3 * 4 * 3-channel, 10-bit ADC 5 * 6 * Copyright (C) 2011, 2012 Roland Stigge <stigge@antcom.de> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 21 */ 22 23 #include <linux/module.h> 24 #include <linux/platform_device.h> 25 #include <linux/interrupt.h> 26 #include <linux/device.h> 27 #include <linux/kernel.h> 28 #include <linux/slab.h> 29 #include <linux/io.h> 30 #include <linux/clk.h> 31 #include <linux/err.h> 32 #include <linux/completion.h> 33 #include <linux/of.h> 34 35 #include <linux/iio/iio.h> 36 #include <linux/iio/sysfs.h> 37 38 /* 39 * LPC32XX registers definitions 40 */ 41 #define LPC32XXAD_SELECT(x) ((x) + 0x04) 42 #define LPC32XXAD_CTRL(x) ((x) + 0x08) 43 #define LPC32XXAD_VALUE(x) ((x) + 0x48) 44 45 /* Bit definitions for LPC32XXAD_SELECT: */ 46 /* constant, always write this value! */ 47 #define LPC32XXAD_REFm 0x00000200 48 /* constant, always write this value! */ 49 #define LPC32XXAD_REFp 0x00000080 50 /* multiple of this is the channel number: 0, 1, 2 */ 51 #define LPC32XXAD_IN 0x00000010 52 /* constant, always write this value! */ 53 #define LPC32XXAD_INTERNAL 0x00000004 54 55 /* Bit definitions for LPC32XXAD_CTRL: */ 56 #define LPC32XXAD_STROBE 0x00000002 57 #define LPC32XXAD_PDN_CTRL 0x00000004 58 59 /* Bit definitions for LPC32XXAD_VALUE: */ 60 #define LPC32XXAD_VALUE_MASK 0x000003FF 61 62 #define LPC32XXAD_NAME "lpc32xx-adc" 63 64 struct lpc32xx_adc_state { 65 void __iomem *adc_base; 66 struct clk *clk; 67 struct completion completion; 68 69 u32 value; 70 }; 71 72 static int lpc32xx_read_raw(struct iio_dev *indio_dev, 73 struct iio_chan_spec const *chan, 74 int *val, 75 int *val2, 76 long mask) 77 { 78 struct lpc32xx_adc_state *st = iio_priv(indio_dev); 79 80 if (mask == IIO_CHAN_INFO_RAW) { 81 mutex_lock(&indio_dev->mlock); 82 clk_prepare_enable(st->clk); 83 /* Measurement setup */ 84 __raw_writel(LPC32XXAD_INTERNAL | (chan->address) | 85 LPC32XXAD_REFp | LPC32XXAD_REFm, 86 LPC32XXAD_SELECT(st->adc_base)); 87 /* Trigger conversion */ 88 __raw_writel(LPC32XXAD_PDN_CTRL | LPC32XXAD_STROBE, 89 LPC32XXAD_CTRL(st->adc_base)); 90 wait_for_completion(&st->completion); /* set by ISR */ 91 clk_disable_unprepare(st->clk); 92 *val = st->value; 93 mutex_unlock(&indio_dev->mlock); 94 95 return IIO_VAL_INT; 96 } 97 98 return -EINVAL; 99 } 100 101 static const struct iio_info lpc32xx_adc_iio_info = { 102 .read_raw = &lpc32xx_read_raw, 103 .driver_module = THIS_MODULE, 104 }; 105 106 #define LPC32XX_ADC_CHANNEL(_index) { \ 107 .type = IIO_VOLTAGE, \ 108 .indexed = 1, \ 109 .channel = _index, \ 110 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 111 .address = LPC32XXAD_IN * _index, \ 112 .scan_index = _index, \ 113 } 114 115 static const struct iio_chan_spec lpc32xx_adc_iio_channels[] = { 116 LPC32XX_ADC_CHANNEL(0), 117 LPC32XX_ADC_CHANNEL(1), 118 LPC32XX_ADC_CHANNEL(2), 119 }; 120 121 static irqreturn_t lpc32xx_adc_isr(int irq, void *dev_id) 122 { 123 struct lpc32xx_adc_state *st = dev_id; 124 125 /* Read value and clear irq */ 126 st->value = __raw_readl(LPC32XXAD_VALUE(st->adc_base)) & 127 LPC32XXAD_VALUE_MASK; 128 complete(&st->completion); 129 130 return IRQ_HANDLED; 131 } 132 133 static int lpc32xx_adc_probe(struct platform_device *pdev) 134 { 135 struct lpc32xx_adc_state *st = NULL; 136 struct resource *res; 137 int retval = -ENODEV; 138 struct iio_dev *iodev = NULL; 139 int irq; 140 141 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 142 if (!res) { 143 dev_err(&pdev->dev, "failed to get platform I/O memory\n"); 144 return -ENXIO; 145 } 146 147 iodev = devm_iio_device_alloc(&pdev->dev, sizeof(*st)); 148 if (!iodev) 149 return -ENOMEM; 150 151 st = iio_priv(iodev); 152 153 st->adc_base = devm_ioremap(&pdev->dev, res->start, 154 resource_size(res)); 155 if (!st->adc_base) { 156 dev_err(&pdev->dev, "failed mapping memory\n"); 157 return -EBUSY; 158 } 159 160 st->clk = devm_clk_get(&pdev->dev, NULL); 161 if (IS_ERR(st->clk)) { 162 dev_err(&pdev->dev, "failed getting clock\n"); 163 return PTR_ERR(st->clk); 164 } 165 166 irq = platform_get_irq(pdev, 0); 167 if (irq <= 0) { 168 dev_err(&pdev->dev, "failed getting interrupt resource\n"); 169 return -ENXIO; 170 } 171 172 retval = devm_request_irq(&pdev->dev, irq, lpc32xx_adc_isr, 0, 173 LPC32XXAD_NAME, st); 174 if (retval < 0) { 175 dev_err(&pdev->dev, "failed requesting interrupt\n"); 176 return retval; 177 } 178 179 platform_set_drvdata(pdev, iodev); 180 181 init_completion(&st->completion); 182 183 iodev->name = LPC32XXAD_NAME; 184 iodev->dev.parent = &pdev->dev; 185 iodev->info = &lpc32xx_adc_iio_info; 186 iodev->modes = INDIO_DIRECT_MODE; 187 iodev->channels = lpc32xx_adc_iio_channels; 188 iodev->num_channels = ARRAY_SIZE(lpc32xx_adc_iio_channels); 189 190 retval = devm_iio_device_register(&pdev->dev, iodev); 191 if (retval) 192 return retval; 193 194 dev_info(&pdev->dev, "LPC32XX ADC driver loaded, IRQ %d\n", irq); 195 196 return 0; 197 } 198 199 #ifdef CONFIG_OF 200 static const struct of_device_id lpc32xx_adc_match[] = { 201 { .compatible = "nxp,lpc3220-adc" }, 202 {}, 203 }; 204 MODULE_DEVICE_TABLE(of, lpc32xx_adc_match); 205 #endif 206 207 static struct platform_driver lpc32xx_adc_driver = { 208 .probe = lpc32xx_adc_probe, 209 .driver = { 210 .name = LPC32XXAD_NAME, 211 .of_match_table = of_match_ptr(lpc32xx_adc_match), 212 }, 213 }; 214 215 module_platform_driver(lpc32xx_adc_driver); 216 217 MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>"); 218 MODULE_DESCRIPTION("LPC32XX ADC driver"); 219 MODULE_LICENSE("GPL"); 220