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/*
* Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver
*
* Copyright 2012 Analog Devices Inc.
* Author: Lars-Peter Clausen <lars@metafoo.de>
*
* Licensed under the GPL-2 or later.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/spi/spi.h>
#include <asm/unaligned.h>
#define SPI_XCOMM_SETTINGS_LEN_OFFSET 10
#define SPI_XCOMM_SETTINGS_3WIRE BIT(6)
#define SPI_XCOMM_SETTINGS_CS_HIGH BIT(5)
#define SPI_XCOMM_SETTINGS_SAMPLE_END BIT(4)
#define SPI_XCOMM_SETTINGS_CPHA BIT(3)
#define SPI_XCOMM_SETTINGS_CPOL BIT(2)
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_MASK 0x3
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_64 0x2
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_16 0x1
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_4 0x0
#define SPI_XCOMM_CMD_UPDATE_CONFIG 0x03
#define SPI_XCOMM_CMD_WRITE 0x04
#define SPI_XCOMM_CLOCK 48000000
struct spi_xcomm {
struct i2c_client *i2c;
uint16_t settings;
uint16_t chipselect;
unsigned int current_speed;
uint8_t buf[63];
};
static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
{
uint16_t settings;
uint8_t *buf = spi_xcomm->buf;
settings = spi_xcomm->settings;
settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
put_unaligned_be16(settings, &buf[1]);
put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
return i2c_master_send(spi_xcomm->i2c, buf, 5);
}
static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
struct spi_device *spi, int is_active)
{
unsigned long cs = spi->chip_select;
uint16_t chipselect = spi_xcomm->chipselect;
if (is_active)
chipselect |= BIT(cs);
else
chipselect &= ~BIT(cs);
spi_xcomm->chipselect = chipselect;
}
static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
struct spi_device *spi, struct spi_transfer *t, unsigned int *settings)
{
if (t->len > 62)
return -EINVAL;
if (t->speed_hz != spi_xcomm->current_speed) {
unsigned int divider;
divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, t->speed_hz);
if (divider >= 64)
*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
else if (divider >= 16)
*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
else
*settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
spi_xcomm->current_speed = t->speed_hz;
}
if (spi->mode & SPI_CPOL)
*settings |= SPI_XCOMM_SETTINGS_CPOL;
else
*settings &= ~SPI_XCOMM_SETTINGS_CPOL;
if (spi->mode & SPI_CPHA)
*settings &= ~SPI_XCOMM_SETTINGS_CPHA;
else
*settings |= SPI_XCOMM_SETTINGS_CPHA;
if (spi->mode & SPI_3WIRE)
*settings |= SPI_XCOMM_SETTINGS_3WIRE;
else
*settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
return 0;
}
static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
struct spi_device *spi, struct spi_transfer *t)
{
int ret;
if (t->tx_buf) {
spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
if (ret < 0)
return ret;
else if (ret != t->len + 1)
return -EIO;
} else if (t->rx_buf) {
ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
if (ret < 0)
return ret;
else if (ret != t->len)
return -EIO;
}
return t->len;
}
static int spi_xcomm_transfer_one(struct spi_master *master,
struct spi_message *msg)
{
struct spi_xcomm *spi_xcomm = spi_master_get_devdata(master);
unsigned int settings = spi_xcomm->settings;
struct spi_device *spi = msg->spi;
unsigned cs_change = 0;
struct spi_transfer *t;
bool is_first = true;
int status = 0;
bool is_last;
spi_xcomm_chipselect(spi_xcomm, spi, true);
list_for_each_entry(t, &msg->transfers, transfer_list) {
if (!t->tx_buf && !t->rx_buf && t->len) {
status = -EINVAL;
break;
}
status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
if (status < 0)
break;
is_last = list_is_last(&t->transfer_list, &msg->transfers);
cs_change = t->cs_change;
if (cs_change ^ is_last)
settings |= BIT(5);
else
settings &= ~BIT(5);
if (t->rx_buf) {
spi_xcomm->settings = settings;
status = spi_xcomm_sync_config(spi_xcomm, t->len);
if (status < 0)
break;
} else if (settings != spi_xcomm->settings || is_first) {
spi_xcomm->settings = settings;
status = spi_xcomm_sync_config(spi_xcomm, 0);
if (status < 0)
break;
}
if (t->len) {
status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
if (status < 0)
break;
if (status > 0)
msg->actual_length += status;
}
status = 0;
if (t->delay_usecs)
udelay(t->delay_usecs);
is_first = false;
}
if (status != 0 || !cs_change)
spi_xcomm_chipselect(spi_xcomm, spi, false);
msg->status = status;
spi_finalize_current_message(master);
return status;
}
static int spi_xcomm_probe(struct i2c_client *i2c,
const struct i2c_device_id *id)
{
struct spi_xcomm *spi_xcomm;
struct spi_master *master;
int ret;
master = spi_alloc_master(&i2c->dev, sizeof(*spi_xcomm));
if (!master)
return -ENOMEM;
spi_xcomm = spi_master_get_devdata(master);
spi_xcomm->i2c = i2c;
master->num_chipselect = 16;
master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
master->bits_per_word_mask = SPI_BPW_MASK(8);
master->flags = SPI_MASTER_HALF_DUPLEX;
master->transfer_one_message = spi_xcomm_transfer_one;
master->dev.of_node = i2c->dev.of_node;
i2c_set_clientdata(i2c, master);
ret = devm_spi_register_master(&i2c->dev, master);
if (ret < 0)
spi_master_put(master);
return ret;
}
static const struct i2c_device_id spi_xcomm_ids[] = {
{ "spi-xcomm" },
{ },
};
static struct i2c_driver spi_xcomm_driver = {
.driver = {
.name = "spi-xcomm",
.owner = THIS_MODULE,
},
.id_table = spi_xcomm_ids,
.probe = spi_xcomm_probe,
};
module_i2c_driver(spi_xcomm_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");
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