[RFC PATCH 03/06] input/rmi4: I2C physical interface

[Christopher Heiny <cheiny@synaptics.com>]

rmi_i2c.c abstracts an RMI4 device on some arbitrary I2C bus as a logical
device in the RMI bus.  It handles reads/writes from/to the RMI4 devices,
and manages the page select register setting (since the meaning of page
select is dependent on the physical layer used to communicate with the RMi4
device).


Signed-off-by: Christopher Heiny <cheiny@synaptics.com>

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Naveen Kumar Gaddipati <naveen.gaddipati@stericsson.com>
Cc: Joeri de Gram <j.de.gram@gmail.com>

Acked-by: Jean Delvare <khali@linux-fr.org>

---

 drivers/input/rmi4/rmi_i2c.c |  490 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 490 insertions(+), 0 deletions(-)

diff --git a/drivers/input/rmi4/rmi_i2c.c b/drivers/input/rmi4/rmi_i2c.c
new file mode 100644
index 0000000..ca32101
--- /dev/null
+++ b/drivers/input/rmi4/rmi_i2c.c
@@ -0,0 +1,490 @@
+/*
+ * Copyright (c) 2011, 2012 Synaptics Incorporated
+ * Copyright (c) 2011 Unixphere
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/kconfig.h>
+#include <linux/lockdep.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/rmi.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include "rmi_driver.h"
+
+#define BUFFER_SIZE_INCREMENT 32
+/**
+ * struct rmi_i2c_data - stores information for i2c communication
+ *
+ * @page_mutex: Locks current page to avoid changing pages in unexpected ways.
+ * @page: Keeps track of the current virtual page
+ * @phys: Pointer to the physical interface
+ *
+ * @tx_buf: Buffer used for transmitting data to the sensor over i2c.
+ * @tx_buf_size: Size of the buffer
+ * @debug_buf: Buffer used for exposing buffer contents using dev_dbg
+ * @debug_buf_size: Size of the debug buffer.
+ *
+ * @comms_debug: Latest data read/written for debugging I2C communications
+ * @debugfs_comms: Debugfs file for debugging I2C communications
+ *
+ */
+struct rmi_i2c_data {
+	struct mutex page_mutex;
+	int page;
+	struct rmi_phys_device *phys;
+
+	u8 *tx_buf;
+	int tx_buf_size;
+	u8 *debug_buf;
+	int debug_buf_size;
+
+	bool comms_debug;
+#ifdef CONFIG_RMI4_DEBUG
+	struct dentry *debugfs_comms;
+#endif
+};
+
+#ifdef CONFIG_RMI4_DEBUG
+
+
+/**
+ * struct i2c_debugfs_data - stores information for debugfs
+ *
+ * @done: Indicates that we are done reading debug data. Subsequent reads
+ * will return EOF.
+ * @i2c_data: Pointer to the i2c data
+ *
+ */
+struct i2c_debugfs_data {
+	bool done;
+	struct rmi_i2c_data *i2c_data;
+};
+
+static int debug_open(struct inode *inodep, struct file *filp)
+{
+	struct i2c_debugfs_data *data;
+
+	data = kzalloc(sizeof(struct i2c_debugfs_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->i2c_data = inodep->i_private;
+	filp->private_data = data;
+	return 0;
+}
+
+static int debug_release(struct inode *inodep, struct file *filp)
+{
+	kfree(filp->private_data);
+	return 0;
+}
+
+static ssize_t comms_debug_read(struct file *filp, char __user *buffer,
+		size_t size, loff_t *offset) {
+	int retval;
+	char *local_buf;
+	struct i2c_debugfs_data *dfs = filp->private_data;
+	struct rmi_i2c_data *data = dfs->i2c_data;
+
+	if (dfs->done)
+		return 0;
+
+	local_buf = kcalloc(size, sizeof(u8), GFP_KERNEL);
+	if (!local_buf)
+		return -ENOMEM;
+
+	dfs->done = 1;
+
+	retval = snprintf(local_buf, PAGE_SIZE, "%u\n", data->comms_debug);
+
+	if (retval <= 0 || copy_to_user(buffer, local_buf, retval))
+		retval = -EFAULT;
+	kfree(local_buf);
+
+	return retval;
+}
+
+static ssize_t comms_debug_write(struct file *filp, const char __user *buffer,
+			   size_t size, loff_t *offset) {
+	int retval;
+	char *local_buf;
+	unsigned int new_value;
+	struct i2c_debugfs_data *dfs = filp->private_data;
+	struct rmi_i2c_data *data = dfs->i2c_data;
+
+	local_buf = kcalloc(size, sizeof(u8), GFP_KERNEL);
+	if (!local_buf)
+		return -ENOMEM;
+	retval = copy_from_user(local_buf, buffer, size);
+	if (retval) {
+		kfree(local_buf);
+		return -EFAULT;
+	}
+
+	retval = sscanf(local_buf, "%u", &new_value);
+	kfree(local_buf);
+	if (retval != 1 || new_value > 1)
+		return -EINVAL;
+
+	data->comms_debug = new_value;
+
+	return size;
+}
+
+
+static const struct file_operations comms_debug_fops = {
+	.owner = THIS_MODULE,
+	.open = debug_open,
+	.release = debug_release,
+	.read = comms_debug_read,
+	.write = comms_debug_write,
+};
+
+static int setup_debugfs(struct rmi_device *rmi_dev, struct rmi_i2c_data *data)
+{
+	if (!rmi_dev->debugfs_root)
+		return -ENODEV;
+
+	data->debugfs_comms = debugfs_create_file("comms_debug", RMI_RW_ATTR,
+			rmi_dev->debugfs_root, data, &comms_debug_fops);
+	if (!data->debugfs_comms || IS_ERR(data->debugfs_comms)) {
+		dev_warn(&rmi_dev->dev, "Failed to create debugfs comms_debug.\n");
+		data->debugfs_comms = NULL;
+	}
+
+	return 0;
+}
+
+static void teardown_debugfs(struct rmi_i2c_data *data)
+{
+	if (data->debugfs_comms)
+		debugfs_remove(data->debugfs_comms);
+}
+#endif
+
+#define COMMS_DEBUG(data) (IS_ENABLED(CONFIG_RMI4_DEBUG) && data->comms_debug)
+
+#define RMI_PAGE_SELECT_REGISTER 0xff
+#define RMI_I2C_PAGE(addr) (((addr) >> 8) & 0xff)
+
+static char *phys_proto_name = "i2c";
+
+/*
+ * rmi_set_page - Set RMI page
+ * @phys: The pointer to the rmi_phys_device struct
+ * @page: The new page address.
+ *
+ * RMI devices have 16-bit addressing, but some of the physical
+ * implementations (like SMBus) only have 8-bit addressing. So RMI implements
+ * a page address at 0xff of every page so we can reliable page addresses
+ * every 256 registers.
+ *
+ * The page_mutex lock must be held when this function is entered.
+ *
+ * Returns zero on success, non-zero on failure.
+ */
+static int rmi_set_page(struct rmi_phys_device *phys, u8 page)
+{
+	struct i2c_client *client = to_i2c_client(phys->dev);
+	struct rmi_i2c_data *data = phys->data;
+	u8 txbuf[2] = {RMI_PAGE_SELECT_REGISTER, page};
+	int retval;
+
+	if (COMMS_DEBUG(data))
+		dev_dbg(&client->dev, "writes 3 bytes: %02x %02x\n",
+			txbuf[0], txbuf[1]);
+	phys->info.tx_count++;
+	phys->info.tx_bytes += sizeof(txbuf);
+	retval = i2c_master_send(client, txbuf, sizeof(txbuf));
+	if (retval != sizeof(txbuf)) {
+		phys->info.tx_errs++;
+		dev_err(&client->dev,
+			"%s: set page failed: %d.", __func__, retval);
+		return (retval < 0) ? retval : -EIO;
+	}
+	data->page = page;
+	return 0;
+}
+
+static int copy_to_debug_buf(struct device *dev, struct rmi_i2c_data *data,
+			     const u8 *buf, const int len) {
+	int i;
+	int n = 0;
+	char *temp;
+	int dbg_size = 3 * len + 1;
+
+	if (!data->debug_buf || data->debug_buf_size < dbg_size) {
+		if (data->debug_buf)
+			devm_kfree(dev, data->debug_buf);
+		data->debug_buf_size = dbg_size + BUFFER_SIZE_INCREMENT;
+		data->debug_buf = devm_kzalloc(dev, data->debug_buf_size,
+					       GFP_KERNEL);
+		if (!data->debug_buf) {
+			data->debug_buf_size = 0;
+			return -ENOMEM;
+		}
+	}
+	temp = data->debug_buf;
+
+	for (i = 0; i < len; i++) {
+		n = sprintf(temp, " %02x", buf[i]);
+		temp += n;
+	}
+
+	return 0;
+}
+
+static int rmi_i2c_write_block(struct rmi_phys_device *phys, u16 addr,
+			       const void *buf, const int len)
+{
+	struct i2c_client *client = to_i2c_client(phys->dev);
+	struct rmi_i2c_data *data = phys->data;
+	int retval;
+	int tx_size = len + 1;
+
+	mutex_lock(&data->page_mutex);
+
+	if (!data->tx_buf || data->tx_buf_size < tx_size) {
+		if (data->tx_buf)
+			devm_kfree(&client->dev, data->tx_buf);
+		data->tx_buf_size = tx_size + BUFFER_SIZE_INCREMENT;
+		data->tx_buf = devm_kzalloc(&client->dev, data->tx_buf_size,
+					    GFP_KERNEL);
+		if (!data->tx_buf) {
+			data->tx_buf_size = 0;
+			retval = -ENOMEM;
+			goto exit;
+		}
+	}
+	data->tx_buf[0] = addr & 0xff;
+	memcpy(data->tx_buf + 1, buf, len);
+
+	if (RMI_I2C_PAGE(addr) != data->page) {
+		retval = rmi_set_page(phys, RMI_I2C_PAGE(addr));
+		if (retval < 0)
+			goto exit;
+	}
+
+	if (COMMS_DEBUG(data)) {
+		retval = copy_to_debug_buf(&client->dev, data, (u8 *) buf, len);
+		if (!retval)
+			dev_dbg(&client->dev, "writes %d bytes at %#06x:%s\n",
+				len, addr, data->debug_buf);
+	}
+
+	phys->info.tx_count++;
+	phys->info.tx_bytes += tx_size;
+	retval = i2c_master_send(client, data->tx_buf, tx_size);
+	if (retval < 0)
+		phys->info.tx_errs++;
+	else
+		retval--; /* don't count the address byte */
+
+exit:
+	mutex_unlock(&data->page_mutex);
+	return retval;
+}
+
+
+static int rmi_i2c_read_block(struct rmi_phys_device *phys, u16 addr,
+			      void *buf, const int len)
+{
+	struct i2c_client *client = to_i2c_client(phys->dev);
+	struct rmi_i2c_data *data = phys->data;
+	u8 txbuf[1] = {addr & 0xff};
+	int retval;
+
+	mutex_lock(&data->page_mutex);
+
+	if (RMI_I2C_PAGE(addr) != data->page) {
+		retval = rmi_set_page(phys, RMI_I2C_PAGE(addr));
+		if (retval < 0)
+			goto exit;
+	}
+
+	if (COMMS_DEBUG(data))
+		dev_dbg(&client->dev, "writes 1 bytes: %02x\n", txbuf[0]);
+
+	phys->info.tx_count++;
+	phys->info.tx_bytes += sizeof(txbuf);
+	retval = i2c_master_send(client, txbuf, sizeof(txbuf));
+	if (retval != sizeof(txbuf)) {
+		phys->info.tx_errs++;
+		retval = (retval < 0) ? retval : -EIO;
+		goto exit;
+	}
+
+	retval = i2c_master_recv(client, (u8 *) buf, len);
+
+	phys->info.rx_count++;
+	phys->info.rx_bytes += len;
+	if (retval < 0)
+		phys->info.rx_errs++;
+	else if (COMMS_DEBUG(data)) {
+		retval = copy_to_debug_buf(&client->dev, data, (u8 *) buf, len);
+		if (!retval)
+			dev_dbg(&client->dev, "read %d bytes at %#06x:%s\n",
+				len, addr, data->debug_buf);
+	}
+
+exit:
+	mutex_unlock(&data->page_mutex);
+	return retval;
+}
+
+static int __devinit rmi_i2c_probe(struct i2c_client *client,
+				  const struct i2c_device_id *id)
+{
+	struct rmi_phys_device *rmi_phys;
+	struct rmi_i2c_data *data;
+	struct rmi_device_platform_data *pdata = client->dev.platform_data;
+	int retval;
+
+	if (!pdata) {
+		dev_err(&client->dev, "no platform data\n");
+		return -EINVAL;
+	}
+	dev_info(&client->dev, "Probing %s at %#02x (IRQ %d).\n",
+		pdata->sensor_name ? pdata->sensor_name : "-no name-",
+		client->addr, pdata->attn_gpio);
+
+	if (pdata->gpio_config) {
+		dev_info(&client->dev, "Configuring GPIOs.\n");
+		retval = pdata->gpio_config(pdata->gpio_data, true);
+		if (retval < 0) {
+			dev_err(&client->dev, "Failed to configure GPIOs, code: %d.\n",
+				retval);
+			return retval;
+		}
+		dev_info(&client->dev, "Done with GPIO configuration.\n");
+	}
+
+	retval = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
+	if (!retval) {
+		dev_err(&client->dev, "i2c_check_functionality error %d.\n",
+			retval);
+		return retval;
+	}
+
+	rmi_phys = devm_kzalloc(&client->dev, sizeof(struct rmi_phys_device),
+				GFP_KERNEL);
+
+	if (!rmi_phys)
+		return -ENOMEM;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct rmi_i2c_data),
+				GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->phys = rmi_phys;
+
+	rmi_phys->data = data;
+	rmi_phys->dev = &client->dev;
+
+	rmi_phys->write_block = rmi_i2c_write_block;
+	rmi_phys->read_block = rmi_i2c_read_block;
+	rmi_phys->info.proto = phys_proto_name;
+
+	mutex_init(&data->page_mutex);
+
+	/* Setting the page to zero will (a) make sure the PSR is in a
+	 * known state, and (b) make sure we can talk to the device.
+	 */
+	retval = rmi_set_page(rmi_phys, 0);
+	if (retval) {
+		dev_err(&client->dev, "Failed to set page select to 0.\n");
+		return retval;
+	}
+
+	retval = rmi_register_phys_device(rmi_phys);
+	if (retval) {
+		dev_err(&client->dev,
+			"failed to register physical driver at 0x%.2X.\n",
+			client->addr);
+		goto err_gpio;
+	}
+	i2c_set_clientdata(client, rmi_phys);
+
+	if (IS_ENABLED(CONFIG_RMI4_DEBUG))
+		retval = setup_debugfs(rmi_phys->rmi_dev, data);
+
+	dev_info(&client->dev, "registered rmi i2c driver at %#04x.\n",
+			client->addr);
+	return 0;
+
+err_gpio:
+	if (pdata->gpio_config)
+		pdata->gpio_config(pdata->gpio_data, false);
+	return retval;
+}
+
+static int __devexit rmi_i2c_remove(struct i2c_client *client)
+{
+	struct rmi_phys_device *phys = i2c_get_clientdata(client);
+	struct rmi_device_platform_data *pd = client->dev.platform_data;
+
+	if (IS_ENABLED(CONFIG_RMI4_DEBUG))
+		teardown_debugfs(phys->data);
+
+	rmi_unregister_phys_device(phys);
+
+	if (pd->gpio_config)
+		pd->gpio_config(&pd->gpio_data, false);
+
+	return 0;
+}
+
+static const struct i2c_device_id rmi_id[] = {
+	{ "rmi_i2c", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, rmi_id);
+
+static struct i2c_driver rmi_i2c_driver = {
+	.driver = {
+		.owner	= THIS_MODULE,
+		.name	= "rmi_i2c"
+	},
+	.id_table	= rmi_id,
+	.probe		= rmi_i2c_probe,
+	.remove		= __devexit_p(rmi_i2c_remove),
+};
+
+static int __init rmi_i2c_init(void)
+{
+	return i2c_add_driver(&rmi_i2c_driver);
+}
+
+static void __exit rmi_i2c_exit(void)
+{
+	i2c_del_driver(&rmi_i2c_driver);
+}
+
+module_init(rmi_i2c_init);
+module_exit(rmi_i2c_exit);
+
+MODULE_AUTHOR("Christopher Heiny <cheiny@synaptics.com>");
+MODULE_DESCRIPTION("RMI I2C driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(RMI_DRIVER_VERSION);