Contributors: 31
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| David Brownell |
957 |
58.96% |
6 |
13.04% |
| Imre Deak |
153 |
9.43% |
1 |
2.17% |
| Lorenzo Bianconi |
115 |
7.09% |
2 |
4.35% |
| Heiner Kallweit |
78 |
4.81% |
1 |
2.17% |
| Mark Brown |
69 |
4.25% |
3 |
6.52% |
| Uwe Kleine-König |
43 |
2.65% |
2 |
4.35% |
| Lukas Wunner |
39 |
2.40% |
1 |
2.17% |
| Linus Walleij |
29 |
1.79% |
1 |
2.17% |
| Andrey Smirnov |
26 |
1.60% |
1 |
2.17% |
| Andy Shevchenko |
17 |
1.05% |
4 |
8.70% |
| Pelle Nilsson |
16 |
0.99% |
1 |
2.17% |
| Kumar Gala |
14 |
0.86% |
1 |
2.17% |
| Anatolij Gustschin |
9 |
0.55% |
1 |
2.17% |
| Guennadi Liakhovetski |
9 |
0.55% |
2 |
4.35% |
| Jan Nikitenko |
8 |
0.49% |
2 |
4.35% |
| Axel Lin |
8 |
0.49% |
2 |
4.35% |
| Nicolas Boichat |
5 |
0.31% |
1 |
2.17% |
| Vitaly Wool |
5 |
0.31% |
1 |
2.17% |
| Hans-Peter Nilsson |
3 |
0.18% |
1 |
2.17% |
| Paul Gortmaker |
3 |
0.18% |
1 |
2.17% |
| Jingoo Han |
3 |
0.18% |
1 |
2.17% |
| Lee Jones |
3 |
0.18% |
1 |
2.17% |
| Sascha Hauer |
2 |
0.12% |
1 |
2.17% |
| Linus Torvalds (pre-git) |
2 |
0.12% |
1 |
2.17% |
| Thomas Gleixner |
1 |
0.06% |
1 |
2.17% |
| Harvey Harrison |
1 |
0.06% |
1 |
2.17% |
| Linus Torvalds |
1 |
0.06% |
1 |
2.17% |
| Fabio Estevam |
1 |
0.06% |
1 |
2.17% |
| Christoph Lameter |
1 |
0.06% |
1 |
2.17% |
| Yue haibing |
1 |
0.06% |
1 |
2.17% |
| David Howells |
1 |
0.06% |
1 |
2.17% |
| Total |
1623 |
|
46 |
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Polling/bitbanging SPI host controller controller driver utilities
*/
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/time64.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#define SPI_BITBANG_CS_DELAY 100
/*----------------------------------------------------------------------*/
/*
* FIRST PART (OPTIONAL): word-at-a-time spi_transfer support.
* Use this for GPIO or shift-register level hardware APIs.
*
* spi_bitbang_cs is in spi_device->controller_state, which is unavailable
* to glue code. These bitbang setup() and cleanup() routines are always
* used, though maybe they're called from controller-aware code.
*
* chipselect() and friends may use spi_device->controller_data and
* controller registers as appropriate.
*
*
* NOTE: SPI controller pins can often be used as GPIO pins instead,
* which means you could use a bitbang driver either to get hardware
* working quickly, or testing for differences that aren't speed related.
*/
struct spi_bitbang_cs {
unsigned nsecs; /* (clock cycle time)/2 */
u32 (*txrx_word)(struct spi_device *spi, unsigned nsecs,
u32 word, u8 bits, unsigned flags);
unsigned (*txrx_bufs)(struct spi_device *,
u32 (*txrx_word)(
struct spi_device *spi,
unsigned nsecs,
u32 word, u8 bits,
unsigned flags),
unsigned, struct spi_transfer *,
unsigned);
};
static unsigned bitbang_txrx_8(
struct spi_device *spi,
u32 (*txrx_word)(struct spi_device *spi,
unsigned nsecs,
u32 word, u8 bits,
unsigned flags),
unsigned ns,
struct spi_transfer *t,
unsigned flags
)
{
unsigned bits = t->bits_per_word;
unsigned count = t->len;
const u8 *tx = t->tx_buf;
u8 *rx = t->rx_buf;
while (likely(count > 0)) {
u8 word = 0;
if (tx)
word = *tx++;
word = txrx_word(spi, ns, word, bits, flags);
if (rx)
*rx++ = word;
count -= 1;
}
return t->len - count;
}
static unsigned bitbang_txrx_16(
struct spi_device *spi,
u32 (*txrx_word)(struct spi_device *spi,
unsigned nsecs,
u32 word, u8 bits,
unsigned flags),
unsigned ns,
struct spi_transfer *t,
unsigned flags
)
{
unsigned bits = t->bits_per_word;
unsigned count = t->len;
const u16 *tx = t->tx_buf;
u16 *rx = t->rx_buf;
while (likely(count > 1)) {
u16 word = 0;
if (tx)
word = *tx++;
word = txrx_word(spi, ns, word, bits, flags);
if (rx)
*rx++ = word;
count -= 2;
}
return t->len - count;
}
static unsigned bitbang_txrx_32(
struct spi_device *spi,
u32 (*txrx_word)(struct spi_device *spi,
unsigned nsecs,
u32 word, u8 bits,
unsigned flags),
unsigned ns,
struct spi_transfer *t,
unsigned flags
)
{
unsigned bits = t->bits_per_word;
unsigned count = t->len;
const u32 *tx = t->tx_buf;
u32 *rx = t->rx_buf;
while (likely(count > 3)) {
u32 word = 0;
if (tx)
word = *tx++;
word = txrx_word(spi, ns, word, bits, flags);
if (rx)
*rx++ = word;
count -= 4;
}
return t->len - count;
}
int spi_bitbang_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
{
struct spi_bitbang_cs *cs = spi->controller_state;
u8 bits_per_word;
u32 hz;
if (t) {
bits_per_word = t->bits_per_word;
hz = t->speed_hz;
} else {
bits_per_word = 0;
hz = 0;
}
/* spi_transfer level calls that work per-word */
if (!bits_per_word)
bits_per_word = spi->bits_per_word;
if (bits_per_word <= 8)
cs->txrx_bufs = bitbang_txrx_8;
else if (bits_per_word <= 16)
cs->txrx_bufs = bitbang_txrx_16;
else if (bits_per_word <= 32)
cs->txrx_bufs = bitbang_txrx_32;
else
return -EINVAL;
/* nsecs = (clock period)/2 */
if (!hz)
hz = spi->max_speed_hz;
if (hz) {
cs->nsecs = (NSEC_PER_SEC / 2) / hz;
if (cs->nsecs > (MAX_UDELAY_MS * NSEC_PER_MSEC))
return -EINVAL;
}
return 0;
}
EXPORT_SYMBOL_GPL(spi_bitbang_setup_transfer);
/*
* spi_bitbang_setup - default setup for per-word I/O loops
*/
int spi_bitbang_setup(struct spi_device *spi)
{
struct spi_bitbang_cs *cs = spi->controller_state;
struct spi_bitbang *bitbang;
bool initial_setup = false;
int retval;
bitbang = spi_controller_get_devdata(spi->controller);
if (!cs) {
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return -ENOMEM;
spi->controller_state = cs;
initial_setup = true;
}
/* per-word shift register access, in hardware or bitbanging */
cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
if (!cs->txrx_word) {
retval = -EINVAL;
goto err_free;
}
if (bitbang->setup_transfer) {
retval = bitbang->setup_transfer(spi, NULL);
if (retval < 0)
goto err_free;
}
dev_dbg(&spi->dev, "%s, %u nsec/bit\n", __func__, 2 * cs->nsecs);
return 0;
err_free:
if (initial_setup)
kfree(cs);
return retval;
}
EXPORT_SYMBOL_GPL(spi_bitbang_setup);
/*
* spi_bitbang_cleanup - default cleanup for per-word I/O loops
*/
void spi_bitbang_cleanup(struct spi_device *spi)
{
kfree(spi->controller_state);
}
EXPORT_SYMBOL_GPL(spi_bitbang_cleanup);
static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
{
struct spi_bitbang_cs *cs = spi->controller_state;
unsigned nsecs = cs->nsecs;
struct spi_bitbang *bitbang;
bitbang = spi_controller_get_devdata(spi->controller);
if (bitbang->set_line_direction) {
int err;
err = bitbang->set_line_direction(spi, !!(t->tx_buf));
if (err < 0)
return err;
}
if (spi->mode & SPI_3WIRE) {
unsigned flags;
flags = t->tx_buf ? SPI_CONTROLLER_NO_RX : SPI_CONTROLLER_NO_TX;
return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t, flags);
}
return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t, 0);
}
/*----------------------------------------------------------------------*/
/*
* SECOND PART ... simple transfer queue runner.
*
* This costs a task context per controller, running the queue by
* performing each transfer in sequence. Smarter hardware can queue
* several DMA transfers at once, and process several controller queues
* in parallel; this driver doesn't match such hardware very well.
*
* Drivers can provide word-at-a-time i/o primitives, or provide
* transfer-at-a-time ones to leverage dma or fifo hardware.
*/
static int spi_bitbang_prepare_hardware(struct spi_controller *spi)
{
struct spi_bitbang *bitbang;
bitbang = spi_controller_get_devdata(spi);
mutex_lock(&bitbang->lock);
bitbang->busy = 1;
mutex_unlock(&bitbang->lock);
return 0;
}
static int spi_bitbang_transfer_one(struct spi_controller *ctlr,
struct spi_device *spi,
struct spi_transfer *transfer)
{
struct spi_bitbang *bitbang = spi_controller_get_devdata(ctlr);
int status = 0;
if (bitbang->setup_transfer) {
status = bitbang->setup_transfer(spi, transfer);
if (status < 0)
goto out;
}
if (transfer->len)
status = bitbang->txrx_bufs(spi, transfer);
if (status == transfer->len)
status = 0;
else if (status >= 0)
status = -EREMOTEIO;
out:
spi_finalize_current_transfer(ctlr);
return status;
}
static int spi_bitbang_unprepare_hardware(struct spi_controller *spi)
{
struct spi_bitbang *bitbang;
bitbang = spi_controller_get_devdata(spi);
mutex_lock(&bitbang->lock);
bitbang->busy = 0;
mutex_unlock(&bitbang->lock);
return 0;
}
static void spi_bitbang_set_cs(struct spi_device *spi, bool enable)
{
struct spi_bitbang *bitbang = spi_controller_get_devdata(spi->controller);
/* SPI core provides CS high / low, but bitbang driver
* expects CS active
* spi device driver takes care of handling SPI_CS_HIGH
*/
enable = (!!(spi->mode & SPI_CS_HIGH) == enable);
ndelay(SPI_BITBANG_CS_DELAY);
bitbang->chipselect(spi, enable ? BITBANG_CS_ACTIVE :
BITBANG_CS_INACTIVE);
ndelay(SPI_BITBANG_CS_DELAY);
}
/*----------------------------------------------------------------------*/
int spi_bitbang_init(struct spi_bitbang *bitbang)
{
struct spi_controller *ctlr = bitbang->ctlr;
bool custom_cs;
if (!ctlr)
return -EINVAL;
/*
* We only need the chipselect callback if we are actually using it.
* If we just use GPIO descriptors, it is surplus. If the
* SPI_CONTROLLER_GPIO_SS flag is set, we always need to call the
* driver-specific chipselect routine.
*/
custom_cs = (!ctlr->use_gpio_descriptors ||
(ctlr->flags & SPI_CONTROLLER_GPIO_SS));
if (custom_cs && !bitbang->chipselect)
return -EINVAL;
mutex_init(&bitbang->lock);
if (!ctlr->mode_bits)
ctlr->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags;
if (ctlr->transfer || ctlr->transfer_one_message)
return -EINVAL;
ctlr->prepare_transfer_hardware = spi_bitbang_prepare_hardware;
ctlr->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware;
ctlr->transfer_one = spi_bitbang_transfer_one;
/*
* When using GPIO descriptors, the ->set_cs() callback doesn't even
* get called unless SPI_CONTROLLER_GPIO_SS is set.
*/
if (custom_cs)
ctlr->set_cs = spi_bitbang_set_cs;
if (!bitbang->txrx_bufs) {
bitbang->use_dma = 0;
bitbang->txrx_bufs = spi_bitbang_bufs;
if (!ctlr->setup) {
if (!bitbang->setup_transfer)
bitbang->setup_transfer =
spi_bitbang_setup_transfer;
ctlr->setup = spi_bitbang_setup;
ctlr->cleanup = spi_bitbang_cleanup;
}
}
return 0;
}
EXPORT_SYMBOL_GPL(spi_bitbang_init);
/**
* spi_bitbang_start - start up a polled/bitbanging SPI host controller driver
* @bitbang: driver handle
*
* Caller should have zero-initialized all parts of the structure, and then
* provided callbacks for chip selection and I/O loops. If the host controller has
* a transfer method, its final step should call spi_bitbang_transfer(); or,
* that's the default if the transfer routine is not initialized. It should
* also set up the bus number and number of chipselects.
*
* For i/o loops, provide callbacks either per-word (for bitbanging, or for
* hardware that basically exposes a shift register) or per-spi_transfer
* (which takes better advantage of hardware like fifos or DMA engines).
*
* Drivers using per-word I/O loops should use (or call) spi_bitbang_setup(),
* spi_bitbang_cleanup() and spi_bitbang_setup_transfer() to handle those SPI
* host controller methods. Those methods are the defaults if the bitbang->txrx_bufs
* routine isn't initialized.
*
* This routine registers the spi_controller, which will process requests in a
* dedicated task, keeping IRQs unblocked most of the time. To stop
* processing those requests, call spi_bitbang_stop().
*
* On success, this routine will take a reference to the controller. The caller
* is responsible for calling spi_bitbang_stop() to decrement the reference and
* spi_controller_put() as counterpart of spi_alloc_host() to prevent a memory
* leak.
*/
int spi_bitbang_start(struct spi_bitbang *bitbang)
{
struct spi_controller *ctlr = bitbang->ctlr;
int ret;
ret = spi_bitbang_init(bitbang);
if (ret)
return ret;
/* driver may get busy before register() returns, especially
* if someone registered boardinfo for devices
*/
ret = spi_register_controller(spi_controller_get(ctlr));
if (ret)
spi_controller_put(ctlr);
return ret;
}
EXPORT_SYMBOL_GPL(spi_bitbang_start);
/*
* spi_bitbang_stop - stops the task providing spi communication
*/
void spi_bitbang_stop(struct spi_bitbang *bitbang)
{
spi_unregister_controller(bitbang->ctlr);
}
EXPORT_SYMBOL_GPL(spi_bitbang_stop);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Utilities for Bitbanging SPI host controllers");