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");