diff options
Diffstat (limited to 'drivers/spi/spi-xcomm.c')
| -rw-r--r-- | drivers/spi/spi-xcomm.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/drivers/spi/spi-xcomm.c b/drivers/spi/spi-xcomm.c new file mode 100644 index 000000000..bb478dccf --- /dev/null +++ b/drivers/spi/spi-xcomm.c @@ -0,0 +1,253 @@ +/* + * 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/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"); |