spi: Add AD-FMCOMMS1-EBZ I2C-SPI bridge driver

This patch adds support for the I2C-SPI bridge which can be found on the Analog
Devices AD-FMCOMMS1-EBZ board.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/spi/Kconfig

@@ -384,6 +384,13 @@ config SPI_TXX9
 	help
 	  SPI driver for Toshiba TXx9 MIPS SoCs
 
+config SPI_XCOMM
+	tristate "Analog Devices AD-FMCOMMS1-EBZ SPI-I2C-bridge driver"
+	depends on I2C
+	help
+	  Support for the SPI-I2C bridge found on the Analog Devices
+	  AD-FMCOMMS1-EBZ board.
+
 config SPI_XILINX
 	tristate "Xilinx SPI controller common module"
 	depends on HAS_IOMEM && EXPERIMENTAL

drivers/spi/Makefile

@@ -61,5 +61,6 @@ obj-$(CONFIG_SPI_TI_SSP)		+= spi-ti-ssp.o
 obj-$(CONFIG_SPI_TLE62X0)		+= spi-tle62x0.o
 obj-$(CONFIG_SPI_TOPCLIFF_PCH)		+= spi-topcliff-pch.o
 obj-$(CONFIG_SPI_TXX9)			+= spi-txx9.o
+obj-$(CONFIG_SPI_XCOMM)		+= spi-xcomm.o
 obj-$(CONFIG_SPI_XILINX)		+= spi-xilinx.o
 

drivers/spi/spi-xcomm.c

+/*
+ * 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)
+{
+	unsigned int speed;
+
+	if ((t->bits_per_word && t->bits_per_word != 8) || t->len > 62)
+		return -EINVAL;
+
+	speed = t->speed_hz ? t->speed_hz : spi->max_speed_hz;
+
+	if (speed != spi_xcomm->current_speed) {
+		unsigned int divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, speed);
+		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 = speed;
+	}
+
+	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;
+
+	is_first = true;
+
+	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_setup(struct spi_device *spi)
+{
+	if (spi->bits_per_word != 8)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int __devinit 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->flags = SPI_MASTER_HALF_DUPLEX;
+	master->setup = spi_xcomm_setup;
+	master->transfer_one_message = spi_xcomm_transfer_one;
+	master->dev.of_node = i2c->dev.of_node;
+	i2c_set_clientdata(i2c, master);
+
+	ret = spi_register_master(master);
+	if (ret < 0)
+		spi_master_put(master);
+
+	return ret;
+}
+
+static int __devexit spi_xcomm_remove(struct i2c_client *i2c)
+{
+	struct spi_master *master = i2c_get_clientdata(i2c);
+
+	spi_unregister_master(master);
+
+	return 0;
+}
+
+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,
+	.remove		= __devexit_p(spi_xcomm_remove),
+};
+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");