mfd: Add support for STMPE SPI interface

Few STMPE controller can have register interface over SPI or I2C. Current
implementation only supports I2C.

This patch adds support for SPI interface for accessing STMPE's address space.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 148 insertions, 0 deletions

diff --git a/drivers/mfd/stmpe-spi.c b/drivers/mfd/stmpe-spi.c
new file mode 100644
index 0000000..53efce4
--- /dev/null
+++ b/drivers/mfd/stmpe-spi.c
@@ -0,0 +1,148 @@
+/*
+ * ST Microelectronics MFD: stmpe's spi client specific driver
+ *
+ * Copyright (C) ST Microelectronics SA 2011
+ *
+ * License Terms: GNU General Public License, version 2
+ * Author: Viresh Kumar <viresh.kumar@st.com> for ST Microelectronics
+ */
+
+#include <linux/spi/spi.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include "stmpe.h"
+
+#define READ_CMD	(1 << 7)
+
+static int spi_reg_read(struct stmpe *stmpe, u8 reg)
+{
+	struct spi_device *spi = stmpe->client;
+	int status = spi_w8r16(spi, reg | READ_CMD);
+
+	return (status < 0) ? status : status >> 8;
+}
+
+static int spi_reg_write(struct stmpe *stmpe, u8 reg, u8 val)
+{
+	struct spi_device *spi = stmpe->client;
+	u16 cmd = (val << 8) | reg;
+
+	return spi_write(spi, (const u8 *)&cmd, 2);
+}
+
+static int spi_block_read(struct stmpe *stmpe, u8 reg, u8 length, u8 *values)
+{
+	int ret, i;
+
+	for (i = 0; i < length; i++) {
+		ret = spi_reg_read(stmpe, reg + i);
+		if (ret < 0)
+			return ret;
+		*(values + i) = ret;
+	}
+
+	return 0;
+}
+
+static int spi_block_write(struct stmpe *stmpe, u8 reg, u8 length,
+		const u8 *values)
+{
+	int ret = 0, i;
+
+	for (i = length; i > 0; i--, reg++) {
+		ret = spi_reg_write(stmpe, reg, *(values + i - 1));
+		if (ret < 0)
+			return ret;
+	}
+
+	return ret;
+}
+
+static void spi_init(struct stmpe *stmpe)
+{
+	struct spi_device *spi = stmpe->client;
+
+	spi->bits_per_word = 8;
+
+	/* This register is only present for stmpe811 */
+	if (stmpe->variant->id_val == 0x0811)
+		spi_reg_write(stmpe, STMPE811_REG_SPI_CFG, spi->mode);
+
+	if (spi_setup(spi) < 0)
+		dev_dbg(&spi->dev, "spi_setup failed\n");
+}
+
+static struct stmpe_client_info spi_ci = {
+	.read_byte = spi_reg_read,
+	.write_byte = spi_reg_write,
+	.read_block = spi_block_read,
+	.write_block = spi_block_write,
+	.init = spi_init,
+};
+
+static int __devinit
+stmpe_spi_probe(struct spi_device *spi)
+{
+	const struct spi_device_id *id = spi_get_device_id(spi);
+
+	/* don't exceed max specified rate - 1MHz - Limitation of STMPE */
+	if (spi->max_speed_hz > 1000000) {
+		dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
+				(spi->max_speed_hz/1000));
+		return -EINVAL;
+	}
+
+	spi_ci.irq = spi->irq;
+	spi_ci.client = spi;
+	spi_ci.dev = &spi->dev;
+
+	return stmpe_probe(&spi_ci, id->driver_data);
+}
+
+static int __devexit stmpe_spi_remove(struct spi_device *spi)
+{
+	struct stmpe *stmpe = dev_get_drvdata(&spi->dev);
+
+	return stmpe_remove(stmpe);
+}
+
+static const struct spi_device_id stmpe_spi_id[] = {
+	{ "stmpe811", STMPE811 },
+	{ "stmpe1601", STMPE1601 },
+	{ "stmpe2401", STMPE2401 },
+	{ "stmpe2403", STMPE2403 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, stmpe_id);
+
+static struct spi_driver stmpe_spi_driver = {
+	.driver = {
+		.name	= "stmpe-spi",
+		.bus	= &spi_bus_type,
+		.owner	= THIS_MODULE,
+#ifdef CONFIG_PM
+		.pm	= &stmpe_dev_pm_ops,
+#endif
+	},
+	.probe		= stmpe_spi_probe,
+	.remove		= __devexit_p(stmpe_spi_remove),
+	.id_table	= stmpe_spi_id,
+};
+
+static int __init stmpe_init(void)
+{
+	return spi_register_driver(&stmpe_spi_driver);
+}
+subsys_initcall(stmpe_init);
+
+static void __exit stmpe_exit(void)
+{
+	spi_unregister_driver(&stmpe_spi_driver);
+}
+module_exit(stmpe_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("STMPE MFD SPI Interface Driver");
+MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");