spi: Master driver for NXP SC18IS602/603
This driver adds support for NXP SC18IS602/603 I2C to SPI bus bridge.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/spi/spi-sc18is602.c b/drivers/spi/spi-sc18is602.c
new file mode 100644
index 0000000..dd989642
--- /dev/null
+++ b/drivers/spi/spi-sc18is602.c
@@ -0,0 +1,364 @@
+/*
+ * NXP SC18IS602/603 SPI driver
+ *
+ * Copyright (C) Guenter Roeck <linux@roeck-us.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/platform_data/sc18is602.h>
+
+enum chips { sc18is602, sc18is602b, sc18is603 };
+
+#define SC18IS602_BUFSIZ 200
+#define SC18IS602_CLOCK 7372000
+
+#define SC18IS602_MODE_CPHA BIT(2)
+#define SC18IS602_MODE_CPOL BIT(3)
+#define SC18IS602_MODE_LSB_FIRST BIT(5)
+#define SC18IS602_MODE_CLOCK_DIV_4 0x0
+#define SC18IS602_MODE_CLOCK_DIV_16 0x1
+#define SC18IS602_MODE_CLOCK_DIV_64 0x2
+#define SC18IS602_MODE_CLOCK_DIV_128 0x3
+
+struct sc18is602 {
+ struct spi_master *master;
+ struct device *dev;
+ u8 ctrl;
+ u32 freq;
+ u32 speed;
+
+ /* I2C data */
+ struct i2c_client *client;
+ enum chips id;
+ u8 buffer[SC18IS602_BUFSIZ + 1];
+ int tlen; /* Data queued for tx in buffer */
+ int rindex; /* Receive data index in buffer */
+};
+
+static int sc18is602_wait_ready(struct sc18is602 *hw, int len)
+{
+ int i, err;
+ int usecs = 1000000 * len / hw->speed + 1;
+ u8 dummy[1];
+
+ for (i = 0; i < 10; i++) {
+ err = i2c_master_recv(hw->client, dummy, 1);
+ if (err >= 0)
+ return 0;
+ usleep_range(usecs, usecs * 2);
+ }
+ return -ETIMEDOUT;
+}
+
+static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg,
+ struct spi_transfer *t, bool do_transfer)
+{
+ unsigned int len = t->len;
+ int ret;
+
+ if (hw->tlen == 0) {
+ /* First byte (I2C command) is chip select */
+ hw->buffer[0] = 1 << msg->spi->chip_select;
+ hw->tlen = 1;
+ hw->rindex = 0;
+ }
+ /*
+ * We can not immediately send data to the chip, since each I2C message
+ * resembles a full SPI message (from CS active to CS inactive).
+ * Enqueue messages up to the first read or until do_transfer is true.
+ */
+ if (t->tx_buf) {
+ memcpy(&hw->buffer[hw->tlen], t->tx_buf, len);
+ hw->tlen += len;
+ if (t->rx_buf)
+ do_transfer = true;
+ else
+ hw->rindex = hw->tlen - 1;
+ } else if (t->rx_buf) {
+ /*
+ * For receive-only transfers we still need to perform a dummy
+ * write to receive data from the SPI chip.
+ * Read data starts at the end of transmit data (minus 1 to
+ * account for CS).
+ */
+ hw->rindex = hw->tlen - 1;
+ memset(&hw->buffer[hw->tlen], 0, len);
+ hw->tlen += len;
+ do_transfer = true;
+ }
+
+ if (do_transfer && hw->tlen > 1) {
+ ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ);
+ if (ret < 0)
+ return ret;
+ ret = i2c_master_send(hw->client, hw->buffer, hw->tlen);
+ if (ret < 0)
+ return ret;
+ if (ret != hw->tlen)
+ return -EIO;
+
+ if (t->rx_buf) {
+ int rlen = hw->rindex + len;
+
+ ret = sc18is602_wait_ready(hw, hw->tlen);
+ if (ret < 0)
+ return ret;
+ ret = i2c_master_recv(hw->client, hw->buffer, rlen);
+ if (ret < 0)
+ return ret;
+ if (ret != rlen)
+ return -EIO;
+ memcpy(t->rx_buf, &hw->buffer[hw->rindex], len);
+ }
+ hw->tlen = 0;
+ }
+ return len;
+}
+
+static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode)
+{
+ u8 ctrl = 0;
+ int ret;
+
+ if (mode & SPI_CPHA)
+ ctrl |= SC18IS602_MODE_CPHA;
+ if (mode & SPI_CPOL)
+ ctrl |= SC18IS602_MODE_CPOL;
+ if (mode & SPI_LSB_FIRST)
+ ctrl |= SC18IS602_MODE_LSB_FIRST;
+
+ /* Find the closest clock speed */
+ if (hz >= hw->freq / 4) {
+ ctrl |= SC18IS602_MODE_CLOCK_DIV_4;
+ hw->speed = hw->freq / 4;
+ } else if (hz >= hw->freq / 16) {
+ ctrl |= SC18IS602_MODE_CLOCK_DIV_16;
+ hw->speed = hw->freq / 16;
+ } else if (hz >= hw->freq / 64) {
+ ctrl |= SC18IS602_MODE_CLOCK_DIV_64;
+ hw->speed = hw->freq / 64;
+ } else {
+ ctrl |= SC18IS602_MODE_CLOCK_DIV_128;
+ hw->speed = hw->freq / 128;
+ }
+
+ /*
+ * Don't do anything if the control value did not change. The initial
+ * value of 0xff for hw->ctrl ensures that the correct mode will be set
+ * with the first call to this function.
+ */
+ if (ctrl == hw->ctrl)
+ return 0;
+
+ ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl);
+ if (ret < 0)
+ return ret;
+
+ hw->ctrl = ctrl;
+
+ return 0;
+}
+
+static int sc18is602_check_transfer(struct spi_device *spi,
+ struct spi_transfer *t, int tlen)
+{
+ int bpw;
+ uint32_t hz;
+
+ if (t && t->len + tlen > SC18IS602_BUFSIZ)
+ return -EINVAL;
+
+ bpw = spi->bits_per_word;
+ if (t && t->bits_per_word)
+ bpw = t->bits_per_word;
+ if (bpw != 8)
+ return -EINVAL;
+
+ hz = spi->max_speed_hz;
+ if (t && t->speed_hz)
+ hz = t->speed_hz;
+ if (hz == 0)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int sc18is602_transfer_one(struct spi_master *master,
+ struct spi_message *m)
+{
+ struct sc18is602 *hw = spi_master_get_devdata(master);
+ struct spi_device *spi = m->spi;
+ struct spi_transfer *t;
+ int status = 0;
+
+ /* SC18IS602 does not support CS2 */
+ if (hw->id == sc18is602 && spi->chip_select == 2) {
+ status = -ENXIO;
+ goto error;
+ }
+
+ hw->tlen = 0;
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ u32 hz = t->speed_hz ? : spi->max_speed_hz;
+ bool do_transfer;
+
+ status = sc18is602_check_transfer(spi, t, hw->tlen);
+ if (status < 0)
+ break;
+
+ status = sc18is602_setup_transfer(hw, hz, spi->mode);
+ if (status < 0)
+ break;
+
+ do_transfer = t->cs_change || list_is_last(&t->transfer_list,
+ &m->transfers);
+
+ if (t->len) {
+ status = sc18is602_txrx(hw, m, t, do_transfer);
+ if (status < 0)
+ break;
+ m->actual_length += status;
+ }
+ status = 0;
+
+ if (t->delay_usecs)
+ udelay(t->delay_usecs);
+ }
+error:
+ m->status = status;
+ spi_finalize_current_message(master);
+
+ return status;
+}
+
+static int sc18is602_setup(struct spi_device *spi)
+{
+ if (!spi->bits_per_word)
+ spi->bits_per_word = 8;
+
+ if (spi->mode & ~(SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST))
+ return -EINVAL;
+
+ return sc18is602_check_transfer(spi, NULL, 0);
+}
+
+static int sc18is602_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct device_node *np = dev->of_node;
+ struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
+ struct sc18is602 *hw;
+ struct spi_master *master;
+ int error;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+ I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+ return -ENODEV;
+
+ master = spi_alloc_master(dev, sizeof(struct sc18is602));
+ if (!master)
+ return -ENOMEM;
+
+ hw = spi_master_get_devdata(master);
+ i2c_set_clientdata(client, hw);
+
+ hw->master = master;
+ hw->client = client;
+ hw->dev = dev;
+ hw->ctrl = 0xff;
+
+ hw->id = id->driver_data;
+
+ switch (hw->id) {
+ case sc18is602:
+ case sc18is602b:
+ master->num_chipselect = 4;
+ hw->freq = SC18IS602_CLOCK;
+ break;
+ case sc18is603:
+ master->num_chipselect = 2;
+ if (pdata) {
+ hw->freq = pdata->clock_frequency;
+ } else {
+ const __be32 *val;
+ int len;
+
+ val = of_get_property(np, "clock-frequency", &len);
+ if (val && len >= sizeof(__be32))
+ hw->freq = be32_to_cpup(val);
+ }
+ if (!hw->freq)
+ hw->freq = SC18IS602_CLOCK;
+ break;
+ }
+ master->bus_num = client->adapter->nr;
+ master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
+ master->setup = sc18is602_setup;
+ master->transfer_one_message = sc18is602_transfer_one;
+ master->dev.of_node = np;
+
+ error = spi_register_master(master);
+ if (error)
+ goto error_reg;
+
+ return 0;
+
+error_reg:
+ spi_master_put(master);
+ return error;
+}
+
+static int sc18is602_remove(struct i2c_client *client)
+{
+ struct sc18is602 *hw = i2c_get_clientdata(client);
+ struct spi_master *master = hw->master;
+
+ spi_unregister_master(master);
+
+ return 0;
+}
+
+static const struct i2c_device_id sc18is602_id[] = {
+ { "sc18is602", sc18is602 },
+ { "sc18is602b", sc18is602b },
+ { "sc18is603", sc18is603 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, sc18is602_id);
+
+static struct i2c_driver sc18is602_driver = {
+ .driver = {
+ .name = "sc18is602",
+ },
+ .probe = sc18is602_probe,
+ .remove = sc18is602_remove,
+ .id_table = sc18is602_id,
+};
+
+module_i2c_driver(sc18is602_driver);
+
+MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver");
+MODULE_AUTHOR("Guenter Roeck");
+MODULE_LICENSE("GPL");