4 * Copyright 2012 Stefan Roese <sr@denx.de>
6 * Licensed under the GPL-2.
9 #include <linux/module.h>
10 #include <linux/platform_device.h>
11 #include <linux/interrupt.h>
12 #include <linux/device.h>
13 #include <linux/kernel.h>
14 #include <linux/slab.h>
16 #include <linux/clk.h>
17 #include <linux/err.h>
18 #include <linux/completion.h>
20 #include <linux/of_address.h>
22 #include <linux/iio/iio.h>
23 #include <linux/iio/sysfs.h>
26 * SPEAR registers definitions
29 #define SCAN_RATE_LO(x) ((x) & 0xFFFF)
30 #define SCAN_RATE_HI(x) (((x) >> 0x10) & 0xFFFF)
31 #define CLK_LOW(x) (((x) & 0xf) << 0)
32 #define CLK_HIGH(x) (((x) & 0xf) << 4)
34 /* Bit definitions for SPEAR_ADC_STATUS */
35 #define START_CONVERSION (1 << 0)
36 #define CHANNEL_NUM(x) ((x) << 1)
37 #define ADC_ENABLE (1 << 4)
38 #define AVG_SAMPLE(x) ((x) << 5)
39 #define VREF_INTERNAL (1 << 9)
41 #define DATA_MASK 0x03ff
44 #define MOD_NAME "spear-adc"
46 #define ADC_CHANNEL_NUM 8
48 #define CLK_MIN 2500000
49 #define CLK_MAX 20000000
51 struct adc_regs_spear3xx {
55 u32 clk; /* Not avail for 1340 & 1310 */
56 u32 ch_ctrl[ADC_CHANNEL_NUM];
57 u32 ch_data[ADC_CHANNEL_NUM];
65 struct adc_regs_spear6xx {
69 u32 ch_ctrl[ADC_CHANNEL_NUM];
70 struct chan_data ch_data[ADC_CHANNEL_NUM];
73 struct chan_data average;
76 struct spear_adc_info {
77 struct device_node *np;
78 struct adc_regs_spear3xx __iomem *adc_base_spear3xx;
79 struct adc_regs_spear6xx __iomem *adc_base_spear6xx;
81 struct completion completion;
90 * Functions to access some SPEAr ADC register. Abstracted into
91 * static inline functions, because of different register offsets
92 * on different SoC variants (SPEAr300 vs SPEAr600 etc).
94 static void spear_adc_set_status(struct spear_adc_info *info, u32 val)
96 __raw_writel(val, &info->adc_base_spear6xx->status);
99 static void spear_adc_set_clk(struct spear_adc_info *info, u32 val)
101 u32 clk_high, clk_low, count;
102 u32 apb_clk = clk_get_rate(info->clk);
104 count = (apb_clk + val - 1) / val;
106 clk_high = count - clk_low;
107 info->current_clk = apb_clk / count;
109 __raw_writel(CLK_LOW(clk_low) | CLK_HIGH(clk_high),
110 &info->adc_base_spear6xx->clk);
113 static void spear_adc_set_ctrl(struct spear_adc_info *info, int n,
116 __raw_writel(val, &info->adc_base_spear6xx->ch_ctrl[n]);
119 static u32 spear_adc_get_average(struct spear_adc_info *info)
121 if (of_device_is_compatible(info->np, "st,spear600-adc")) {
122 return __raw_readl(&info->adc_base_spear6xx->average.msb) &
125 return __raw_readl(&info->adc_base_spear3xx->average) &
130 static void spear_adc_set_scanrate(struct spear_adc_info *info, u32 rate)
132 if (of_device_is_compatible(info->np, "st,spear600-adc")) {
133 __raw_writel(SCAN_RATE_LO(rate),
134 &info->adc_base_spear6xx->scan_rate_lo);
135 __raw_writel(SCAN_RATE_HI(rate),
136 &info->adc_base_spear6xx->scan_rate_hi);
138 __raw_writel(rate, &info->adc_base_spear3xx->scan_rate);
142 static int spear_read_raw(struct iio_dev *indio_dev,
143 struct iio_chan_spec const *chan,
148 struct spear_adc_info *info = iio_priv(indio_dev);
152 case IIO_CHAN_INFO_RAW:
153 mutex_lock(&indio_dev->mlock);
155 status = CHANNEL_NUM(chan->channel) |
156 AVG_SAMPLE(info->avg_samples) |
157 START_CONVERSION | ADC_ENABLE;
158 if (info->vref_external == 0)
159 status |= VREF_INTERNAL;
161 spear_adc_set_status(info, status);
162 wait_for_completion(&info->completion); /* set by ISR */
165 mutex_unlock(&indio_dev->mlock);
169 case IIO_CHAN_INFO_SCALE:
170 *val = info->vref_external;
172 return IIO_VAL_FRACTIONAL_LOG2;
178 #define SPEAR_ADC_CHAN(idx) { \
179 .type = IIO_VOLTAGE, \
181 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
182 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
190 static const struct iio_chan_spec spear_adc_iio_channels[] = {
201 static irqreturn_t spear_adc_isr(int irq, void *dev_id)
203 struct spear_adc_info *info = (struct spear_adc_info *)dev_id;
205 /* Read value to clear IRQ */
206 info->value = spear_adc_get_average(info);
207 complete(&info->completion);
212 static int spear_adc_configure(struct spear_adc_info *info)
217 spear_adc_set_status(info, 0);
218 __raw_writel(0, &info->adc_base_spear6xx->clk);
219 for (i = 0; i < 8; i++)
220 spear_adc_set_ctrl(info, i, 0);
221 spear_adc_set_scanrate(info, 0);
223 spear_adc_set_clk(info, info->sampling_freq);
228 static ssize_t spear_adc_read_frequency(struct device *dev,
229 struct device_attribute *attr,
232 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
233 struct spear_adc_info *info = iio_priv(indio_dev);
235 return sprintf(buf, "%d\n", info->current_clk);
238 static ssize_t spear_adc_write_frequency(struct device *dev,
239 struct device_attribute *attr,
243 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
244 struct spear_adc_info *info = iio_priv(indio_dev);
245 u32 clk_high, clk_low, count;
246 u32 apb_clk = clk_get_rate(info->clk);
250 ret = kstrtoul(buf, 10, &lval);
254 mutex_lock(&indio_dev->mlock);
256 if ((lval < CLK_MIN) || (lval > CLK_MAX)) {
261 count = (apb_clk + lval - 1) / lval;
263 clk_high = count - clk_low;
264 info->current_clk = apb_clk / count;
265 spear_adc_set_clk(info, lval);
268 mutex_unlock(&indio_dev->mlock);
270 return ret ? ret : len;
273 static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
274 spear_adc_read_frequency,
275 spear_adc_write_frequency);
277 static struct attribute *spear_attributes[] = {
278 &iio_dev_attr_sampling_frequency.dev_attr.attr,
282 static const struct attribute_group spear_attribute_group = {
283 .attrs = spear_attributes,
286 static const struct iio_info spear_adc_iio_info = {
287 .read_raw = &spear_read_raw,
288 .attrs = &spear_attribute_group,
289 .driver_module = THIS_MODULE,
292 static int spear_adc_probe(struct platform_device *pdev)
294 struct device_node *np = pdev->dev.of_node;
295 struct device *dev = &pdev->dev;
296 struct spear_adc_info *info;
297 struct iio_dev *iodev = NULL;
301 iodev = devm_iio_device_alloc(dev, sizeof(struct spear_adc_info));
303 dev_err(dev, "failed allocating iio device\n");
307 info = iio_priv(iodev);
311 * SPEAr600 has a different register layout than other SPEAr SoC's
312 * (e.g. SPEAr3xx). Let's provide two register base addresses
313 * to support multi-arch kernels.
315 info->adc_base_spear6xx = of_iomap(np, 0);
316 if (!info->adc_base_spear6xx) {
317 dev_err(dev, "failed mapping memory\n");
320 info->adc_base_spear3xx =
321 (struct adc_regs_spear3xx __iomem *)info->adc_base_spear6xx;
323 info->clk = clk_get(dev, NULL);
324 if (IS_ERR(info->clk)) {
325 dev_err(dev, "failed getting clock\n");
329 ret = clk_prepare_enable(info->clk);
331 dev_err(dev, "failed enabling clock\n");
335 irq = platform_get_irq(pdev, 0);
337 dev_err(dev, "failed getting interrupt resource\n");
342 ret = devm_request_irq(dev, irq, spear_adc_isr, 0, MOD_NAME, info);
344 dev_err(dev, "failed requesting interrupt\n");
348 if (of_property_read_u32(np, "sampling-frequency",
349 &info->sampling_freq)) {
350 dev_err(dev, "sampling-frequency missing in DT\n");
356 * Optional avg_samples defaults to 0, resulting in single data
359 of_property_read_u32(np, "average-samples", &info->avg_samples);
362 * Optional vref_external defaults to 0, resulting in internal vref
365 of_property_read_u32(np, "vref-external", &info->vref_external);
367 spear_adc_configure(info);
369 platform_set_drvdata(pdev, iodev);
371 init_completion(&info->completion);
373 iodev->name = MOD_NAME;
374 iodev->dev.parent = dev;
375 iodev->info = &spear_adc_iio_info;
376 iodev->modes = INDIO_DIRECT_MODE;
377 iodev->channels = spear_adc_iio_channels;
378 iodev->num_channels = ARRAY_SIZE(spear_adc_iio_channels);
380 ret = iio_device_register(iodev);
384 dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq);
389 clk_disable_unprepare(info->clk);
393 iounmap(info->adc_base_spear6xx);
397 static int spear_adc_remove(struct platform_device *pdev)
399 struct iio_dev *iodev = platform_get_drvdata(pdev);
400 struct spear_adc_info *info = iio_priv(iodev);
402 iio_device_unregister(iodev);
403 clk_disable_unprepare(info->clk);
405 iounmap(info->adc_base_spear6xx);
411 static const struct of_device_id spear_adc_dt_ids[] = {
412 { .compatible = "st,spear600-adc", },
415 MODULE_DEVICE_TABLE(of, spear_adc_dt_ids);
418 static struct platform_driver spear_adc_driver = {
419 .probe = spear_adc_probe,
420 .remove = spear_adc_remove,
423 .owner = THIS_MODULE,
424 .of_match_table = of_match_ptr(spear_adc_dt_ids),
428 module_platform_driver(spear_adc_driver);
430 MODULE_AUTHOR("Stefan Roese <sr@denx.de>");
431 MODULE_DESCRIPTION("SPEAr ADC driver");
432 MODULE_LICENSE("GPL");