2 * sca3000_ring.c -- support VTI sca3000 series accelerometers via SPI
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 as published by
6 * the Free Software Foundation.
8 * Copyright (c) 2009 Jonathan Cameron <jic23@cam.ac.uk>
12 #include <linux/interrupt.h>
13 #include <linux/gpio.h>
15 #include <linux/device.h>
16 #include <linux/slab.h>
17 #include <linux/kernel.h>
18 #include <linux/spi/spi.h>
19 #include <linux/sysfs.h>
23 #include "../ring_generic.h"
24 #include "../ring_hw.h"
30 * The internal ring buffer doesn't actually change what it holds depending
31 * on which signals are enabled etc, merely whether you can read them.
32 * As such the scan mode selection is somewhat different than for a software
33 * ring buffer and changing it actually covers any data already in the buffer.
34 * Currently scan elements aren't configured so it doesn't matter.
38 * sca3000_rip_hw_rb() - main ring access function, pulls data from ring
40 * @count: number of samples to try and pull
41 * @data: output the actual samples pulled from the hw ring
42 * @dead_offset: cheating a bit here: Set to 1 so as to allow for the
43 * leading byte used in bus comms.
45 * Currently does not provide timestamps. As the hardware doesn't add them they
46 * can only be inferred aproximately from ring buffer events such as 50% full
47 * and knowledge of when buffer was last emptied. This is left to userspace.
49 static int sca3000_rip_hw_rb(struct iio_ring_buffer
*r
,
50 size_t count
, u8
**data
, int *dead_offset
)
52 struct iio_hw_ring_buffer
*hw_ring
= iio_to_hw_ring_buf(r
);
53 struct iio_dev
*indio_dev
= hw_ring
->private;
54 struct sca3000_state
*st
= indio_dev
->dev_data
;
56 int ret
, num_available
, num_read
= 0;
57 int bytes_per_sample
= 1;
62 mutex_lock(&st
->lock
);
63 /* Check how much data is available:
64 * RFC: Implement an ioctl to not bother checking whether there
65 * is enough data in the ring? Afterall, if we are responding
66 * to an interrupt we have a minimum content guaranteed so it
67 * seems slight silly to waste time checking it is there.
69 ret
= sca3000_read_data(st
,
70 SCA3000_REG_ADDR_BUF_COUNT
,
75 num_available
= rx
[1];
76 /* num_available is the total number of samples available
77 * i.e. number of time points * number of channels.
80 if (count
> num_available
* bytes_per_sample
)
81 num_read
= num_available
*bytes_per_sample
;
83 num_read
= count
- (count
% (bytes_per_sample
));
85 /* Avoid the read request byte */
87 ret
= sca3000_read_data(st
,
88 SCA3000_REG_ADDR_RING_OUT
,
91 mutex_unlock(&st
->lock
);
93 return ret
? ret
: num_read
;
96 /* This is only valid with all 3 elements enabled */
97 static int sca3000_ring_get_length(struct iio_ring_buffer
*r
)
102 /* only valid if resolution is kept at 11bits */
103 static int sca3000_ring_get_bpd(struct iio_ring_buffer
*r
)
107 static void sca3000_ring_release(struct device
*dev
)
109 struct iio_ring_buffer
*r
= to_iio_ring_buffer(dev
);
110 kfree(iio_to_hw_ring_buf(r
));
113 static IIO_RING_ENABLE_ATTR
;
114 static IIO_RING_BPS_ATTR
;
115 static IIO_RING_LENGTH_ATTR
;
118 * sca3000_show_ring_bpse() -sysfs function to query bits per sample from ring
119 * @dev: ring buffer device
120 * @attr: this device attribute
121 * @buf: buffer to write to
123 static ssize_t
sca3000_show_ring_bpse(struct device
*dev
,
124 struct device_attribute
*attr
,
129 struct iio_ring_buffer
*r
= dev_get_drvdata(dev
);
130 struct sca3000_state
*st
= r
->indio_dev
->dev_data
;
132 mutex_lock(&st
->lock
);
133 ret
= sca3000_read_data(st
, SCA3000_REG_ADDR_MODE
, &rx
, 1);
136 len
= sprintf(buf
, "%d\n", (rx
[1] & SCA3000_RING_BUF_8BIT
) ? 8 : 11);
139 mutex_unlock(&st
->lock
);
141 return ret
? ret
: len
;
145 * sca3000_store_ring_bpse() - bits per scan element
146 * @dev: ring buffer device
147 * @attr: attribute called from
148 * @buf: input from userspace
149 * @len: length of input
151 static ssize_t
sca3000_store_ring_bpse(struct device
*dev
,
152 struct device_attribute
*attr
,
156 struct iio_ring_buffer
*r
= dev_get_drvdata(dev
);
157 struct sca3000_state
*st
= r
->indio_dev
->dev_data
;
161 ret
= strict_strtol(buf
, 10, &val
);
165 mutex_lock(&st
->lock
);
167 ret
= sca3000_read_data(st
, SCA3000_REG_ADDR_MODE
, &rx
, 1);
171 ret
= sca3000_write_reg(st
, SCA3000_REG_ADDR_MODE
,
172 rx
[1] | SCA3000_RING_BUF_8BIT
);
176 ret
= sca3000_write_reg(st
, SCA3000_REG_ADDR_MODE
,
177 rx
[1] & ~SCA3000_RING_BUF_8BIT
);
184 mutex_unlock(&st
->lock
);
186 return ret
? ret
: len
;
189 static IIO_CONST_ATTR(bpse_available
, "8 11");
191 static IIO_DEV_ATTR_BPSE(S_IRUGO
| S_IWUSR
,
192 sca3000_show_ring_bpse
,
193 sca3000_store_ring_bpse
);
196 * Ring buffer attributes
197 * This device is a bit unusual in that the sampling frequency and bpse
198 * only apply to the ring buffer. At all times full rate and accuracy
199 * is available via direct reading from registers.
201 static struct attribute
*iio_ring_attributes
[] = {
202 &dev_attr_length
.attr
,
204 &dev_attr_ring_enable
.attr
,
205 &iio_dev_attr_bpse
.dev_attr
.attr
,
206 &iio_const_attr_bpse_available
.dev_attr
.attr
,
210 static struct attribute_group sca3000_ring_attr
= {
211 .attrs
= iio_ring_attributes
,
214 static const struct attribute_group
*sca3000_ring_attr_groups
[] = {
219 static struct device_type sca3000_ring_type
= {
220 .release
= sca3000_ring_release
,
221 .groups
= sca3000_ring_attr_groups
,
224 static struct iio_ring_buffer
*sca3000_rb_allocate(struct iio_dev
*indio_dev
)
226 struct iio_ring_buffer
*buf
;
227 struct iio_hw_ring_buffer
*ring
;
229 ring
= kzalloc(sizeof *ring
, GFP_KERNEL
);
232 ring
->private = indio_dev
;
234 iio_ring_buffer_init(buf
, indio_dev
);
235 buf
->dev
.type
= &sca3000_ring_type
;
236 device_initialize(&buf
->dev
);
237 buf
->dev
.parent
= &indio_dev
->dev
;
238 dev_set_drvdata(&buf
->dev
, (void *)buf
);
243 static inline void sca3000_rb_free(struct iio_ring_buffer
*r
)
246 iio_put_ring_buffer(r
);
249 int sca3000_configure_ring(struct iio_dev
*indio_dev
)
251 indio_dev
->ring
= sca3000_rb_allocate(indio_dev
);
252 if (indio_dev
->ring
== NULL
)
254 indio_dev
->modes
|= INDIO_RING_HARDWARE_BUFFER
;
256 indio_dev
->ring
->access
.rip_lots
= &sca3000_rip_hw_rb
;
257 indio_dev
->ring
->access
.get_length
= &sca3000_ring_get_length
;
258 indio_dev
->ring
->access
.get_bpd
= &sca3000_ring_get_bpd
;
263 void sca3000_unconfigure_ring(struct iio_dev
*indio_dev
)
265 sca3000_rb_free(indio_dev
->ring
);
269 int __sca3000_hw_ring_state_set(struct iio_dev
*indio_dev
, bool state
)
271 struct sca3000_state
*st
= indio_dev
->dev_data
;
275 mutex_lock(&st
->lock
);
276 ret
= sca3000_read_data(st
, SCA3000_REG_ADDR_MODE
, &rx
, 1);
280 printk(KERN_INFO
"supposedly enabling ring buffer\n");
281 ret
= sca3000_write_reg(st
,
282 SCA3000_REG_ADDR_MODE
,
283 (rx
[1] | SCA3000_RING_BUF_ENABLE
));
285 ret
= sca3000_write_reg(st
,
286 SCA3000_REG_ADDR_MODE
,
287 (rx
[1] & ~SCA3000_RING_BUF_ENABLE
));
290 mutex_unlock(&st
->lock
);
295 * sca3000_hw_ring_preenable() hw ring buffer preenable function
297 * Very simple enable function as the chip will allows normal reads
298 * during ring buffer operation so as long as it is indeed running
299 * before we notify the core, the precise ordering does not matter.
301 static int sca3000_hw_ring_preenable(struct iio_dev
*indio_dev
)
303 return __sca3000_hw_ring_state_set(indio_dev
, 1);
306 static int sca3000_hw_ring_postdisable(struct iio_dev
*indio_dev
)
308 return __sca3000_hw_ring_state_set(indio_dev
, 0);
311 void sca3000_register_ring_funcs(struct iio_dev
*indio_dev
)
313 indio_dev
->ring
->preenable
= &sca3000_hw_ring_preenable
;
314 indio_dev
->ring
->postdisable
= &sca3000_hw_ring_postdisable
;
318 * sca3000_ring_int_process() ring specific interrupt handling.
320 * This is only split from the main interrupt handler so as to
321 * reduce the amount of code if the ring buffer is not enabled.
323 void sca3000_ring_int_process(u8 val
, struct iio_ring_buffer
*ring
)
325 if (val
& SCA3000_INT_STATUS_THREE_QUARTERS
)
326 iio_push_or_escallate_ring_event(ring
,
327 IIO_EVENT_CODE_RING_75_FULL
,
329 else if (val
& SCA3000_INT_STATUS_HALF
)
330 iio_push_ring_event(ring
,
331 IIO_EVENT_CODE_RING_50_FULL
, 0);