Message-Id: <1363218651-22457-3-git-send-email-bleung@chromium.org>
Date:	Wed, 13 Mar 2013 16:50:49 -0700
From:	Benson Leung <bleung@...omium.org>
To:	rydberg@...omail.se, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, dmitry.torokhov@...il.com
Cc:	bleung@...omium.org, olofj@...omium.org, djkurtz@...omium.org,
	dudl@...ress.com
Subject: [PATCH 2/4] Input: cyapa - Firmware update via request firmware

From: Daniel Kurtz <djkurtz@...omium.org>

Use the kernel request_firmware API to allow a hotplug script to load new
firmware into CYAPA device.  When request_firmware is called by a driver,
the kernel creates 'loading' and 'data' sysfs entries, and generates a
firmware udev event containing the name of a file ("cyapa.bin").

A udev rule can detect this event and use the sysfs entries to provide the
driver with the contents of a binary image firmware image. For instance,
the gentoo distribution includes /lib/udev/rules.d/50-firmware.rules,
which looks in /lib/firmware/ for a file matching the requested filename,
and sends the file to the driver using its sysfs entries.

Userspace can initiate the firmware update procedure by copying cyapa.bin
to /lib/firmware, and then writing anything to the device sysfs attribute:
  /sys/bus/i2c/devices/7-0067/update_fw

Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>
Signed-off-by: Benson Leung <bleung@...omium.org>
---
 drivers/input/mouse/cyapa.c | 351 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 351 insertions(+)

diff --git a/drivers/input/mouse/cyapa.c b/drivers/input/mouse/cyapa.c
index a631aca..e622c25 100644
--- a/drivers/input/mouse/cyapa.c
+++ b/drivers/input/mouse/cyapa.c
@@ -15,6 +15,7 @@
  */
 
 #include <linux/delay.h>
+#include <linux/firmware.h>
 #include <linux/i2c.h>
 #include <linux/input.h>
 #include <linux/input/mt.h>
@@ -116,6 +117,9 @@
 #define BL_STATUS_SIZE  3  /* length of bootloader status registers */
 #define BLK_HEAD_BYTES 32
 
+/* Macro for register map group offset. */
+#define CYAPA_REG_MAP_SIZE  256
+
 #define PRODUCT_ID_SIZE  16
 #define QUERY_DATA_SIZE  27
 #define REG_PROTOCOL_GEN_QUERY_OFFSET  20
@@ -220,6 +224,8 @@ struct cyapa {
 	int physical_size_y;
 };
 
+static const u8 bl_activate[] = { 0x00, 0xff, 0x38, 0x00, 0x01, 0x02, 0x03,
+		0x04, 0x05, 0x06, 0x07 };
 static const u8 bl_deactivate[] = { 0x00, 0xff, 0x3b, 0x00, 0x01, 0x02, 0x03,
 		0x04, 0x05, 0x06, 0x07 };
 static const u8 bl_exit[] = { 0x00, 0xff, 0xa5, 0x00, 0x01, 0x02, 0x03, 0x04,
@@ -316,6 +322,41 @@ static const struct cyapa_cmd_len cyapa_smbus_cmds[] = {
 	{ CYAPA_SMBUS_BLK_HEAD, 16 },
 };
 
+#define CYAPA_FW_NAME		"cyapa.bin"
+#define CYAPA_FW_BLOCK_SIZE	64
+#define CYAPA_FW_HDR_START	0x0780
+#define CYAPA_FW_HDR_BLOCK_COUNT  2
+#define CYAPA_FW_HDR_BLOCK_START  (CYAPA_FW_HDR_START / CYAPA_FW_BLOCK_SIZE)
+#define CYAPA_FW_HDR_SIZE	(CYAPA_FW_HDR_BLOCK_COUNT * \
+				 CYAPA_FW_BLOCK_SIZE)
+#define CYAPA_FW_DATA_START	0x0800
+#define CYAPA_FW_DATA_BLOCK_COUNT  480
+#define CYAPA_FW_DATA_BLOCK_START  (CYAPA_FW_DATA_START / CYAPA_FW_BLOCK_SIZE)
+#define CYAPA_FW_DATA_SIZE	(CYAPA_FW_DATA_BLOCK_COUNT * \
+				 CYAPA_FW_BLOCK_SIZE)
+#define CYAPA_FW_SIZE		(CYAPA_FW_HDR_SIZE + CYAPA_FW_DATA_SIZE)
+#define CYAPA_CMD_LEN		16
+
+#define BYTE_PER_LINE  8
+void cyapa_dump_data(struct cyapa *cyapa, size_t length, const u8 *data)
+{
+#ifdef DEBUG
+	struct device *dev = &cyapa->client->dev;
+	int i;
+	char buf[BYTE_PER_LINE * 3 + 1];
+	char *s = buf;
+
+	for (i = 0; i < length; i++) {
+		s += sprintf(s, " %02x", data[i]);
+		if ((i + 1) == length || ((i + 1) % BYTE_PER_LINE) == 0) {
+			dev_dbg(dev, "%s\n", buf);
+			s = buf;
+		}
+	}
+#endif
+}
+#undef BYTE_PER_LINE
+
 static ssize_t cyapa_i2c_reg_read_block(struct cyapa *cyapa, u8 reg, size_t len,
 					u8 *values)
 {
@@ -498,6 +539,75 @@ static int cyapa_poll_state(struct cyapa *cyapa, unsigned int timeout)
 	return (ret == -EAGAIN || ret == -ETIMEDOUT) ? -ETIMEDOUT : ret;
 }
 
+/*
+ * Enter bootloader by soft resetting the device.
+ *
+ * If device is already in the bootloader, the function just returns.
+ * Otherwise, reset the device; after reset, device enters bootloader idle
+ * state immediately.
+ *
+ * Also, if device was unregister device from input core.  Device will
+ * re-register after it is detected following resumption of operational mode.
+ *
+ * Returns:
+ *   0 on success
+ *   -EAGAIN  device was reset, but is not now in bootloader idle state
+ *   < 0 if the device never responds within the timeout
+ */
+static int cyapa_bl_enter(struct cyapa *cyapa)
+{
+	int ret;
+
+	if (cyapa->input) {
+		disable_irq(cyapa->irq);
+		input_unregister_device(cyapa->input);
+		cyapa->input = NULL;
+	}
+
+	ret = cyapa_get_state(cyapa);
+	if (ret < 0)
+		return ret;
+	if (cyapa->state == CYAPA_STATE_BL_IDLE)
+		return 0;
+
+	if (cyapa->state != CYAPA_STATE_OP)
+		return -EAGAIN;
+
+	cyapa->state = CYAPA_STATE_NO_DEVICE;
+	ret = cyapa_write_byte(cyapa, CYAPA_CMD_SOFT_RESET, 0x01);
+	if (ret < 0)
+		return -EIO;
+
+	usleep_range(25000, 50000);
+	ret = cyapa_get_state(cyapa);
+	if (ret < 0)
+		return ret;
+	if (cyapa->state != CYAPA_STATE_BL_IDLE)
+		return -EAGAIN;
+
+	return 0;
+}
+
+static int cyapa_bl_activate(struct cyapa *cyapa)
+{
+	int ret;
+
+	ret = cyapa_i2c_reg_write_block(cyapa, 0, sizeof(bl_activate),
+					bl_activate);
+	if (ret < 0)
+		return ret;
+
+	/* Wait for bootloader to activate; takes between 2 and 12 seconds */
+	msleep(2000);
+	ret = cyapa_poll_state(cyapa, 10000);
+	if (ret < 0)
+		return ret;
+	if (cyapa->state != CYAPA_STATE_BL_ACTIVE)
+		return -EAGAIN;
+
+	return 0;
+}
+
 static int cyapa_bl_deactivate(struct cyapa *cyapa)
 {
 	int ret;
@@ -682,6 +792,154 @@ static int cyapa_check_is_operational(struct cyapa *cyapa)
 	return 0;
 }
 
+static u16 cyapa_csum(const u8 *buf, size_t count)
+{
+	int i;
+	u16 csum = 0;
+
+	for (i = 0; i < count; i++)
+		csum += buf[i];
+
+	return csum;
+}
+
+/*
+ * Write a |len| byte long buffer |buf| to the device, by chopping it up into a
+ * sequence of smaller |CYAPA_CMD_LEN|-length write commands.
+ *
+ * The data bytes for a write command are prepended with the 1-byte offset
+ * of the data relative to the start of |buf|.
+ */
+static int cyapa_write_buffer(struct cyapa *cyapa, const u8 *buf, size_t len)
+{
+	int ret;
+	size_t i;
+	unsigned char cmd[CYAPA_CMD_LEN + 1];
+	size_t cmd_len;
+
+	for (i = 0; i < len; i += CYAPA_CMD_LEN) {
+		const u8 *payload = &buf[i];
+		cmd_len = (len - i >= CYAPA_CMD_LEN) ? CYAPA_CMD_LEN : len - i;
+		cmd[0] = i;
+		memcpy(&cmd[1], payload, cmd_len);
+
+		ret = cyapa_i2c_reg_write_block(cyapa, 0, cmd_len + 1, cmd);
+		if (ret < 0)
+			return ret;
+	}
+	return 0;
+}
+
+/*
+ * A firmware block write command writes 64 bytes of data to a single flash
+ * page in the device.  The 78-byte block write command has the format:
+ *   <0xff> <CMD> <Key> <Start> <Data> <Data-Checksum> <CMD Checksum>
+ *
+ *  <0xff>  - every command starts with 0xff
+ *  <CMD>   - the write command value is 0x39
+ *  <Key>   - write commands include an 8-byte key: { 00 01 02 03 04 05 06 07 }
+ *  <Block> - Memory Block number (address / 64) (16-bit, big-endian)
+ *  <Data>  - 64 bytes of firmware image data
+ *  <Data Checksum> - sum of 64 <Data> bytes, modulo 0xff
+ *  <CMD Checksum> - sum of 77 bytes, from 0xff to <Data Checksum>
+ *
+ * Each write command is split into 5 i2c write transactions of up to 16 bytes.
+ * Each transaction starts with an i2c register offset: (00, 10, 20, 30, 40).
+ */
+static int cyapa_write_fw_block(struct cyapa *cyapa, u16 block, const u8 *data)
+{
+	int ret;
+	u8 cmd[78];
+	u8 status[BL_STATUS_SIZE];
+	int tries = 3;
+
+	/* set write command and security key bytes. */
+	cmd[0] = 0xff;
+	cmd[1] = 0x39;
+	cmd[2] = 0x00;
+	cmd[3] = 0x01;
+	cmd[4] = 0x02;
+	cmd[5] = 0x03;
+	cmd[6] = 0x04;
+	cmd[7] = 0x05;
+	cmd[8] = 0x06;
+	cmd[9] = 0x07;
+	cmd[10] = block >> 8;
+	cmd[11] = block;
+	memcpy(&cmd[12], data, CYAPA_FW_BLOCK_SIZE);
+	cmd[76] = cyapa_csum(data, CYAPA_FW_BLOCK_SIZE);
+	cmd[77] = cyapa_csum(cmd, sizeof(cmd) - 1);
+
+	ret = cyapa_write_buffer(cyapa, cmd, sizeof(cmd));
+	if (ret)
+		return ret;
+
+	/* wait for write to finish */
+	do {
+		usleep_range(10000, 20000);
+
+		/* check block write command result status. */
+		ret = cyapa_i2c_reg_read_block(cyapa, BL_HEAD_OFFSET,
+					       BL_STATUS_SIZE, status);
+		if (ret != BL_STATUS_SIZE)
+			return (ret < 0) ? ret : -EIO;
+		ret = (status[1] == 0x10 && status[2] == 0x20) ? 0 : -EIO;
+	} while (--tries && ret);
+
+	return ret;
+}
+
+/*
+ * Verify the integrity of a CYAPA firmware image file.
+ *
+ * The firmware image file is 30848 bytes, composed of 482 64-byte blocks.
+ *
+ * The first 2 blocks are the firmware header.
+ * The next 480 blocks are the firmware image.
+ *
+ * The first two bytes of the header hold the header checksum, computed by
+ * summing the other 126 bytes of the header.
+ * The last two bytes of the header hold the firmware image checksum, computed
+ * by summing the 30720 bytes of the image modulo 0xffff.
+ *
+ * Both checksums are stored little-endian.
+ */
+static int cyapa_check_fw(struct cyapa *cyapa, const struct firmware *fw)
+{
+	struct device *dev = &cyapa->client->dev;
+	u16 csum;
+	u16 csum_expected;
+
+	/* Firmware must match exact 30848 bytes = 482 64-byte blocks. */
+	if (fw->size != CYAPA_FW_SIZE) {
+		dev_err(dev, "invalid firmware size = %zu, expected %u.\n",
+			fw->size, CYAPA_FW_SIZE);
+		return -EINVAL;
+	}
+
+	/* Verify header block */
+	csum_expected = (fw->data[0] << 8) | fw->data[1];
+	csum = cyapa_csum(&fw->data[2], CYAPA_FW_HDR_SIZE - 2);
+	if (csum != csum_expected) {
+		dev_err(dev,
+			"invalid fw header checksum = %04x, expected: %04x\n",
+			csum, csum_expected);
+		return -EINVAL;
+	}
+
+	/* Verify firmware image */
+	csum_expected = (fw->data[CYAPA_FW_HDR_SIZE - 2] << 8) |
+			 fw->data[CYAPA_FW_HDR_SIZE - 1];
+	csum = cyapa_csum(&fw->data[CYAPA_FW_HDR_SIZE], CYAPA_FW_DATA_SIZE);
+	if (csum != csum_expected) {
+		dev_err(dev,
+			"invalid fw header checksum = %04x, expected: %04x\n",
+			csum, csum_expected);
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static irqreturn_t cyapa_irq(int irq, void *dev_id)
 {
 	struct cyapa *cyapa = dev_id;
@@ -857,6 +1115,94 @@ static void cyapa_detect(struct cyapa *cyapa)
 	}
 }
 
+static int cyapa_firmware(struct cyapa *cyapa, const char *fw_name)
+{
+	struct device *dev = &cyapa->client->dev;
+	int ret;
+	const struct firmware *fw;
+	int i;
+
+	ret = request_firmware(&fw, fw_name, dev);
+	if (ret) {
+		dev_err(dev, "Could not load firmware from %s, %d\n",
+			fw_name, ret);
+		return ret;
+	}
+
+	ret = cyapa_check_fw(cyapa, fw);
+	if (ret) {
+		dev_err(dev, "Invalid CYAPA firmware image: %s\n", fw_name);
+		goto done;
+	}
+
+	ret = cyapa_bl_enter(cyapa);
+	if (ret)
+		goto err_detect;
+
+	ret = cyapa_bl_activate(cyapa);
+	if (ret)
+		goto err_detect;
+
+	/* First write data, starting at byte 128  of fw->data */
+	for (i = 0; i < CYAPA_FW_DATA_BLOCK_COUNT; i++) {
+		size_t block = CYAPA_FW_DATA_BLOCK_START + i;
+		size_t addr = (i + CYAPA_FW_HDR_BLOCK_COUNT) *
+				CYAPA_FW_BLOCK_SIZE;
+		const u8 *data = &fw->data[addr];
+		ret = cyapa_write_fw_block(cyapa, block, data);
+		if (ret)
+			goto err_detect;
+	}
+
+	/* Then write checksum */
+	for (i = 0; i < CYAPA_FW_HDR_BLOCK_COUNT; i++) {
+		size_t block = CYAPA_FW_HDR_BLOCK_START + i;
+		size_t addr = i * CYAPA_FW_BLOCK_SIZE;
+		const u8 *data = &fw->data[addr];
+		ret = cyapa_write_fw_block(cyapa, block, data);
+		if (ret)
+			goto err_detect;
+	}
+
+err_detect:
+	cyapa_detect(cyapa);
+
+done:
+	release_firmware(fw);
+	return ret;
+}
+
+/*
+ * Sysfs Interface.
+ */
+static ssize_t cyapa_update_fw_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct cyapa *cyapa = dev_get_drvdata(dev);
+	const char *fw_name = CYAPA_FW_NAME;
+	int ret;
+
+	ret = cyapa_firmware(cyapa, fw_name);
+	if (ret)
+		dev_err(dev, "firmware update failed, %d\n", ret);
+	else
+		dev_dbg(dev, "firmware update succeeded\n");
+
+	return ret ? ret : count;
+}
+
+static DEVICE_ATTR(update_fw, S_IWUSR, NULL, cyapa_update_fw_store);
+
+static struct attribute *cyapa_sysfs_entries[] = {
+	&dev_attr_update_fw.attr,
+	NULL,
+};
+
+static const struct attribute_group cyapa_sysfs_group = {
+	.attrs = cyapa_sysfs_entries,
+};
+
 static int cyapa_probe(struct i2c_client *client,
 		       const struct i2c_device_id *dev_id)
 {
@@ -902,6 +1248,9 @@ static int cyapa_probe(struct i2c_client *client,
 		goto err_unregister_device;
 	}
 
+	if (sysfs_create_group(&client->dev.kobj, &cyapa_sysfs_group))
+		dev_warn(dev, "error creating sysfs entries.\n");
+
 	return 0;
 
 err_unregister_device:
@@ -916,6 +1265,8 @@ static int cyapa_remove(struct i2c_client *client)
 {
 	struct cyapa *cyapa = i2c_get_clientdata(client);
 
+	sysfs_remove_group(&client->dev.kobj, &cyapa_sysfs_group);
+
 	free_irq(cyapa->irq, cyapa);
 	input_unregister_device(cyapa->input);
 	cyapa_set_power_mode(cyapa, PWR_MODE_OFF);
-- 
1.8.1.3

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