kernel-aes67/drivers/mfd/mc13xxx-spi.c
Philippe Rétornaz ada72d0a93 mfd: mc13xxx workaround SPI hardware bug on i.Mx
The MC13xxx PMIC is mainly used on i.Mx SoC. On those SoC the SPI
hardware will deassert CS line as soon as the SPI FIFO is empty.
The MC13xxx hardware is very sensitive to CS line change as it
corrupts the transfer if CS is deasserted in the middle of a register
read or write.
It is not possible to use the CS line as a GPIO on some SoC, so we
need to workaround this by implementing a single SPI transfer to
access the PMIC.

Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Marc Reilly <marc@cpdesign.com.au>
Signed-off-by: Philippe Rétornaz <philippe.retornaz@epfl.ch>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
2012-07-09 00:16:25 +02:00

204 lines
5.1 KiB
C

/*
* Copyright 2009-2010 Pengutronix
* Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
*
* loosely based on an earlier driver that has
* Copyright 2009 Pengutronix, Sascha Hauer <s.hauer@pengutronix.de>
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License version 2 as published by the
* Free Software Foundation.
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/interrupt.h>
#include <linux/mfd/core.h>
#include <linux/mfd/mc13xxx.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>
#include <linux/err.h>
#include <linux/spi/spi.h>
#include "mc13xxx.h"
static const struct spi_device_id mc13xxx_device_id[] = {
{
.name = "mc13783",
.driver_data = MC13XXX_ID_MC13783,
}, {
.name = "mc13892",
.driver_data = MC13XXX_ID_MC13892,
}, {
/* sentinel */
}
};
MODULE_DEVICE_TABLE(spi, mc13xxx_device_id);
static const struct of_device_id mc13xxx_dt_ids[] = {
{ .compatible = "fsl,mc13783", .data = (void *) MC13XXX_ID_MC13783, },
{ .compatible = "fsl,mc13892", .data = (void *) MC13XXX_ID_MC13892, },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mc13xxx_dt_ids);
static struct regmap_config mc13xxx_regmap_spi_config = {
.reg_bits = 7,
.pad_bits = 1,
.val_bits = 24,
.write_flag_mask = 0x80,
.max_register = MC13XXX_NUMREGS,
.cache_type = REGCACHE_NONE,
.use_single_rw = 1,
};
static int mc13xxx_spi_read(void *context, const void *reg, size_t reg_size,
void *val, size_t val_size)
{
unsigned char w[4] = { *((unsigned char *) reg), 0, 0, 0};
unsigned char r[4];
unsigned char *p = val;
struct device *dev = context;
struct spi_device *spi = to_spi_device(dev);
struct spi_transfer t = {
.tx_buf = w,
.rx_buf = r,
.len = 4,
};
struct spi_message m;
int ret;
if (val_size != 3 || reg_size != 1)
return -ENOTSUPP;
spi_message_init(&m);
spi_message_add_tail(&t, &m);
ret = spi_sync(spi, &m);
memcpy(p, &r[1], 3);
return ret;
}
static int mc13xxx_spi_write(void *context, const void *data, size_t count)
{
struct device *dev = context;
struct spi_device *spi = to_spi_device(dev);
if (count != 4)
return -ENOTSUPP;
return spi_write(spi, data, count);
}
/*
* We cannot use regmap-spi generic bus implementation here.
* The MC13783 chip will get corrupted if CS signal is deasserted
* and on i.Mx31 SoC (the target SoC for MC13783 PMIC) the SPI controller
* has the following errata (DSPhl22960):
* "The CSPI negates SS when the FIFO becomes empty with
* SSCTL= 0. Software cannot guarantee that the FIFO will not
* drain because of higher priority interrupts and the
* non-realtime characteristics of the operating system. As a
* result, the SS will negate before all of the data has been
* transferred to/from the peripheral."
* We workaround this by accessing the SPI controller with a
* single transfert.
*/
static struct regmap_bus regmap_mc13xxx_bus = {
.write = mc13xxx_spi_write,
.read = mc13xxx_spi_read,
};
static int mc13xxx_spi_probe(struct spi_device *spi)
{
const struct of_device_id *of_id;
struct spi_driver *sdrv = to_spi_driver(spi->dev.driver);
struct mc13xxx *mc13xxx;
struct mc13xxx_platform_data *pdata = dev_get_platdata(&spi->dev);
int ret;
of_id = of_match_device(mc13xxx_dt_ids, &spi->dev);
if (of_id)
sdrv->id_table = &mc13xxx_device_id[(enum mc13xxx_id) of_id->data];
mc13xxx = kzalloc(sizeof(*mc13xxx), GFP_KERNEL);
if (!mc13xxx)
return -ENOMEM;
dev_set_drvdata(&spi->dev, mc13xxx);
spi->mode = SPI_MODE_0 | SPI_CS_HIGH;
mc13xxx->dev = &spi->dev;
mutex_init(&mc13xxx->lock);
mc13xxx->regmap = regmap_init(&spi->dev, &regmap_mc13xxx_bus, &spi->dev,
&mc13xxx_regmap_spi_config);
if (IS_ERR(mc13xxx->regmap)) {
ret = PTR_ERR(mc13xxx->regmap);
dev_err(mc13xxx->dev, "Failed to initialize register map: %d\n",
ret);
dev_set_drvdata(&spi->dev, NULL);
kfree(mc13xxx);
return ret;
}
ret = mc13xxx_common_init(mc13xxx, pdata, spi->irq);
if (ret) {
dev_set_drvdata(&spi->dev, NULL);
} else {
const struct spi_device_id *devid =
spi_get_device_id(spi);
if (!devid || devid->driver_data != mc13xxx->ictype)
dev_warn(mc13xxx->dev,
"device id doesn't match auto detection!\n");
}
return ret;
}
static int __devexit mc13xxx_spi_remove(struct spi_device *spi)
{
struct mc13xxx *mc13xxx = dev_get_drvdata(&spi->dev);
mc13xxx_common_cleanup(mc13xxx);
return 0;
}
static struct spi_driver mc13xxx_spi_driver = {
.id_table = mc13xxx_device_id,
.driver = {
.name = "mc13xxx",
.owner = THIS_MODULE,
.of_match_table = mc13xxx_dt_ids,
},
.probe = mc13xxx_spi_probe,
.remove = __devexit_p(mc13xxx_spi_remove),
};
static int __init mc13xxx_init(void)
{
return spi_register_driver(&mc13xxx_spi_driver);
}
subsys_initcall(mc13xxx_init);
static void __exit mc13xxx_exit(void)
{
spi_unregister_driver(&mc13xxx_spi_driver);
}
module_exit(mc13xxx_exit);
MODULE_DESCRIPTION("Core driver for Freescale MC13XXX PMIC");
MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
MODULE_LICENSE("GPL v2");