[PATCH 3/4] usb: typec: ucsi: stm32g0: add bootloader support

[Fabrice Gasnier]

STM32G0 comes with STM32 bootloader in its system memory. Add support
for some I2C bootloader commands as described in application notes
AN2606 and AN4221, to enable STM32G0 UCSI firmware update.

Upon probing, the driver needs to know the STM32G0 state:
- In bootloader mode, STM32 G0 answers at i2c addr 0x51.
- In running mode, STM32 G0 firmware may answer at two address.
  - The main address specified in DT is used for UCSI.
  - 0x51 addr can be re-used for FW controls like getting software version
    or jump to booloader request.

So probe using the main firmware i2c address first, before attempting
bootloader address (e.g. check for blank, erased or previously aborted
firmware update).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxxxxxxx>
---
 drivers/usb/typec/ucsi/ucsi_stm32g0.c | 533 +++++++++++++++++++++++++-
 1 file changed, 520 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi_stm32g0.c b/drivers/usb/typec/ucsi/ucsi_stm32g0.c
index d1f22cee8c6c9..91222f4e07aee 100644
--- a/drivers/usb/typec/ucsi/ucsi_stm32g0.c
+++ b/drivers/usb/typec/ucsi/ucsi_stm32g0.c
@@ -6,21 +6,324 @@
  * Author: Fabrice Gasnier <fabrice.gasnier@xxxxxxxxxxx>.
  */
 
+#include <linux/delay.h>
+#include <linux/firmware.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <asm/unaligned.h>
 
 #include "ucsi.h"
 
+/* STM32G0 I2C bootloader addr: 0b1010001x (See AN2606) */
+#define STM32G0_I2C_BL_ADDR	(0xa2 >> 1)
+
+/* STM32G0 I2C bootloader max data size */
+#define STM32G0_I2C_BL_SZ	256
+
+/* STM32 I2C bootloader commands (See AN4221) */
+#define STM32_CMD_GVR		0x01	/* Gets the bootloader version */
+#define STM32_CMD_GVR_LEN	1
+#define STM32_CMD_RM		0x11	/* Reag memory */
+#define STM32_CMD_WM		0x31	/* Write memory */
+#define STM32_CMD_ADDR_LEN	5	/* Address len for go, mem write... */
+#define STM32_CMD_ERASE		0x44	/* Erase page, bank or all */
+#define STM32_CMD_ERASE_SPECIAL_LEN	3
+#define STM32_CMD_GLOBAL_MASS_ERASE	0xffff /* All-bank erase */
+
+/* STM32 I2C bootloader answer status */
+#define STM32G0_I2C_BL_ACK	0x79
+#define STM32G0_I2C_BL_NACK	0x1f
+#define STM32G0_I2C_BL_BUSY	0x76
+
+/* STM32G0 flash definitions */
+#define STM32G0_USER_OPTION_BYTES	0x1fff7800
+#define STM32G0_USER_OB_NBOOT0		BIT(26)
+#define STM32G0_USER_OB_NBOOT_SEL	BIT(24)
+#define STM32G0_USER_OB_BOOT_MAIN	(STM32G0_USER_OB_NBOOT0 | STM32G0_USER_OB_NBOOT_SEL)
+#define STM32G0_MAIN_MEM_ADDR		0x08000000
+
+/* STM32 Firmware definitions: additional commands */
+#define STM32G0_FW_GETVER	0x00	/* Gets the firmware version */
+#define STM32G0_FW_GETVER_LEN	4
+#define STM32G0_FW_RSTGOBL	0x21	/* Reset and go to bootloader */
+#define STM32G0_FW_KEYWORD	0xa56959a6
+
+/* ucsi_stm32g0_fw_info located at the end of the firmware */
+struct ucsi_stm32g0_fw_info {
+	u32 version;
+	u32 keyword;
+};
+
 struct ucsi_stm32g0 {
 	struct i2c_client *client;
+	struct i2c_client *i2c_bl;
+	bool in_bootloader;
+	u8 bl_version;
 	struct completion complete;
 	struct device *dev;
 	unsigned long flags;
+	const char *fw_name;
 	struct ucsi *ucsi;
 };
 
+/*
+ * Bootloader commands helpers:
+ * - send command (2 bytes)
+ * - check ack
+ * Then either:
+ * - receive data
+ * - receive data + check ack
+ * - send data + check ack
+ * These operations depends on the command and have various length.
+ */
+static int ucsi_stm32g0_bl_check_ack(struct ucsi *ucsi)
+{
+	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
+	struct i2c_client *client = g0->i2c_bl;
+	unsigned char ack;
+	struct i2c_msg msg[] = {
+		{
+			.addr	= client->addr,
+			.flags  = I2C_M_RD,
+			.len	= 1,
+			.buf	= &ack,
+		},
+	};
+	int ret;
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret != ARRAY_SIZE(msg)) {
+		dev_err(g0->dev, "i2c bl ack (%02x), error: %d\n", client->addr, ret);
+
+		return ret < 0 ? ret : -EIO;
+	}
+
+	/* The 'ack' byte should contain bootloader answer: ack/nack/busy */
+	switch (ack) {
+	case STM32G0_I2C_BL_ACK:
+		return 0;
+	case STM32G0_I2C_BL_NACK:
+		return -ENOENT;
+	case STM32G0_I2C_BL_BUSY:
+		return -EBUSY;
+	default:
+		dev_err(g0->dev, "i2c bl ack (%02x), invalid byte: %02x\n",
+			client->addr, ack);
+		return -EINVAL;
+	}
+}
+
+static int ucsi_stm32g0_bl_cmd_check_ack(struct ucsi *ucsi, unsigned int cmd, bool check_ack)
+{
+	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
+	struct i2c_client *client = g0->i2c_bl;
+	unsigned char buf[2];
+	struct i2c_msg msg[] = {
+		{
+			.addr	= client->addr,
+			.flags  = 0,
+			.len	= sizeof(buf),
+			.buf	= buf,
+		},
+	};
+	int ret;
+
+	/*
+	 * Send STM32 bootloader command format is two bytes:
+	 * - command code
+	 * - XOR'ed command code
+	 */
+	buf[0] = cmd;
+	buf[1] = cmd ^ 0xff;
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret != ARRAY_SIZE(msg)) {
+		dev_dbg(g0->dev, "i2c bl cmd %d (%02x), error: %d\n", cmd, client->addr, ret);
+
+		return ret < 0 ? ret : -EIO;
+	}
+
+	if (check_ack)
+		return ucsi_stm32g0_bl_check_ack(ucsi);
+
+	return 0;
+}
+
+static int ucsi_stm32g0_bl_cmd(struct ucsi *ucsi, unsigned int cmd)
+{
+	return ucsi_stm32g0_bl_cmd_check_ack(ucsi, cmd, true);
+}
+
+static int ucsi_stm32g0_bl_rcv_check_ack(struct ucsi *ucsi, void *data, size_t len, bool check_ack)
+{
+	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
+	struct i2c_client *client = g0->i2c_bl;
+	struct i2c_msg msg[] = {
+		{
+			.addr	= client->addr,
+			.flags  = I2C_M_RD,
+			.len	= len,
+			.buf	= data,
+		},
+	};
+	int ret;
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret != ARRAY_SIZE(msg)) {
+		dev_err(g0->dev, "i2c bl rcv %02x, error: %d\n", client->addr, ret);
+
+		return ret < 0 ? ret : -EIO;
+	}
+
+	if (check_ack)
+		return ucsi_stm32g0_bl_check_ack(ucsi);
+
+	return 0;
+}
+
+static int ucsi_stm32g0_bl_rcv(struct ucsi *ucsi, void *data, size_t len)
+{
+	return ucsi_stm32g0_bl_rcv_check_ack(ucsi, data, len, true);
+}
+
+static int ucsi_stm32g0_bl_rcv_woack(struct ucsi *ucsi, void *data, size_t len)
+{
+	return ucsi_stm32g0_bl_rcv_check_ack(ucsi, data, len, false);
+}
+
+static int ucsi_stm32g0_bl_send(struct ucsi *ucsi, void *data, size_t len)
+{
+	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
+	struct i2c_client *client = g0->i2c_bl;
+	struct i2c_msg msg[] = {
+		{
+			.addr	= client->addr,
+			.flags  = 0,
+			.len	= len,
+			.buf	= data,
+		},
+	};
+	int ret;
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret != ARRAY_SIZE(msg)) {
+		dev_err(g0->dev, "i2c bl send %02x, error: %d\n", client->addr, ret);
+
+		return ret < 0 ? ret : -EIO;
+	}
+
+	return ucsi_stm32g0_bl_check_ack(ucsi);
+}
+
+/* Bootloader commands */
+static int ucsi_stm32g0_bl_get_version(struct ucsi *ucsi, u8 *bl_version)
+{
+	int ret;
+
+	ret = ucsi_stm32g0_bl_cmd(ucsi, STM32_CMD_GVR);
+	if (ret)
+		return ret;
+
+	return ucsi_stm32g0_bl_rcv(ucsi, bl_version, STM32_CMD_GVR_LEN);
+}
+
+static int ucsi_stm32g0_bl_send_addr(struct ucsi *ucsi, u32 addr)
+{
+	u8 data8[STM32_CMD_ADDR_LEN];
+
+	/* Address format: 4 bytes addr (MSB first) + XOR'ed addr bytes */
+	put_unaligned_be32(addr, data8);
+	data8[4] = data8[0] ^ data8[1] ^ data8[2] ^ data8[3];
+
+	return ucsi_stm32g0_bl_send(ucsi, data8, STM32_CMD_ADDR_LEN);
+}
+
+static int ucsi_stm32g0_bl_global_mass_erase(struct ucsi *ucsi)
+{
+	u8 data8[4];
+	u16 *data16 = (u16 *)&data8[0];
+	int ret;
+
+	data16[0] = STM32_CMD_GLOBAL_MASS_ERASE;
+	data8[2] = data8[0] ^ data8[1];
+
+	ret = ucsi_stm32g0_bl_cmd(ucsi, STM32_CMD_ERASE);
+	if (ret)
+		return ret;
+
+	return ucsi_stm32g0_bl_send(ucsi, data8, STM32_CMD_ERASE_SPECIAL_LEN);
+}
+
+static int ucsi_stm32g0_bl_write(struct ucsi *ucsi, u32 addr, const void *data, size_t len)
+{
+	u8 *data8;
+	int i, ret;
+
+	if (!len || len > STM32G0_I2C_BL_SZ)
+		return -EINVAL;
+
+	/* Write memory: len bytes -1, data up to 256 bytes + XOR'ed bytes */
+	data8 = kzalloc(STM32G0_I2C_BL_SZ + 2, GFP_KERNEL);
+	if (!data8)
+		return -ENOMEM;
+
+	ret = ucsi_stm32g0_bl_cmd(ucsi, STM32_CMD_WM);
+	if (ret)
+		goto free;
+
+	ret = ucsi_stm32g0_bl_send_addr(ucsi, addr);
+	if (ret)
+		goto free;
+
+	data8[0] = len - 1;
+	memcpy(data8 + 1, data, len);
+	data8[len + 1] = data8[0];
+	for (i = 1; i <= len; i++)
+		data8[len + 1] ^= data8[i];
+
+	ret = ucsi_stm32g0_bl_send(ucsi, data8, len + 2);
+free:
+	kfree(data8);
+
+	return ret;
+}
+
+static int ucsi_stm32g0_bl_read(struct ucsi *ucsi, u32 addr, void *data, size_t len)
+{
+	int ret;
+
+	if (!len || len > STM32G0_I2C_BL_SZ)
+		return -EINVAL;
+
+	ret = ucsi_stm32g0_bl_cmd(ucsi, STM32_CMD_RM);
+	if (ret)
+		return ret;
+
+	ret = ucsi_stm32g0_bl_send_addr(ucsi, addr);
+	if (ret)
+		return ret;
+
+	ret = ucsi_stm32g0_bl_cmd(ucsi, len - 1);
+	if (ret)
+		return ret;
+
+	return ucsi_stm32g0_bl_rcv_woack(ucsi, data, len);
+}
+
+/* Firmware commands (the same address as the bootloader) */
+static int ucsi_stm32g0_fw_cmd(struct ucsi *ucsi, unsigned int cmd)
+{
+	return ucsi_stm32g0_bl_cmd_check_ack(ucsi, cmd, false);
+}
+
+static int ucsi_stm32g0_fw_rcv(struct ucsi *ucsi, void *data, size_t len)
+{
+	return ucsi_stm32g0_bl_rcv_woack(ucsi, data, len);
+}
+
+/* UCSI ops */
 static int ucsi_stm32g0_read(struct ucsi *ucsi, unsigned int offset, void *val, size_t len)
 {
 	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
@@ -133,6 +436,191 @@ static const struct ucsi_operations ucsi_stm32g0_ops = {
 	.async_write = ucsi_stm32g0_async_write,
 };
 
+static int ucsi_stm32g0_register(struct ucsi *ucsi)
+{
+	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
+	struct i2c_client *client = g0->client;
+	int ret;
+
+	/* Request alert interrupt */
+	ret = request_threaded_irq(client->irq, NULL, ucsi_stm32g0_irq_handler, IRQF_ONESHOT,
+				   dev_name(g0->dev), g0);
+	if (ret) {
+		dev_err(g0->dev, "request IRQ failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = ucsi_register(ucsi);
+	if (ret) {
+		dev_err_probe(g0->dev, ret, "ucsi_register failed\n");
+		free_irq(client->irq, g0);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void ucsi_stm32g0_unregister(struct ucsi *ucsi)
+{
+	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
+	struct i2c_client *client = g0->client;
+
+	ucsi_unregister(ucsi);
+	free_irq(client->irq, g0);
+}
+
+static void ucsi_stm32g0_fw_cb(const struct firmware *fw, void *context)
+{
+	struct ucsi_stm32g0 *g0;
+	const u8 *data, *end;
+	const struct ucsi_stm32g0_fw_info *fw_info;
+	u32 addr = STM32G0_MAIN_MEM_ADDR, ob, fw_version;
+	int ret, size;
+
+	if (!context)
+		return;
+
+	g0 = ucsi_get_drvdata(context);
+
+	if (!fw)
+		goto fw_release;
+
+	fw_info = (struct ucsi_stm32g0_fw_info *)(fw->data + fw->size - sizeof(*fw_info));
+
+	if (!g0->in_bootloader) {
+		/* Read running firmware version */
+		ret = ucsi_stm32g0_fw_cmd(g0->ucsi, STM32G0_FW_GETVER);
+		if (ret) {
+			dev_err(g0->dev, "Get version cmd failed %d\n", ret);
+			goto fw_release;
+		}
+		ret = ucsi_stm32g0_fw_rcv(g0->ucsi, &fw_version,
+					  STM32G0_FW_GETVER_LEN);
+		if (ret) {
+			dev_err(g0->dev, "Get version failed %d\n", ret);
+			goto fw_release;
+		}
+
+		/* Sanity check on keyword and firmware version */
+		if (fw_info->keyword != STM32G0_FW_KEYWORD || fw_info->version == fw_version)
+			goto fw_release;
+
+		dev_info(g0->dev, "Flashing FW: %08x (%08x cur)\n", fw_info->version, fw_version);
+
+		/* Switch to bootloader mode */
+		ucsi_stm32g0_unregister(g0->ucsi);
+		ret = ucsi_stm32g0_fw_cmd(g0->ucsi, STM32G0_FW_RSTGOBL);
+		if (ret) {
+			dev_err(g0->dev, "bootloader cmd failed %d\n", ret);
+			goto fw_release;
+		}
+		g0->in_bootloader = true;
+
+		/* STM32G0 reboot delay */
+		msleep(100);
+	}
+
+	ret = ucsi_stm32g0_bl_global_mass_erase(g0->ucsi);
+	if (ret) {
+		dev_err(g0->dev, "Erase failed %d\n", ret);
+		goto fw_release;
+	}
+
+	data = fw->data;
+	end = fw->data + fw->size;
+	while (data < end) {
+		if ((end - data) < STM32G0_I2C_BL_SZ)
+			size = end - data;
+		else
+			size = STM32G0_I2C_BL_SZ;
+
+		ret = ucsi_stm32g0_bl_write(g0->ucsi, addr, data, size);
+		if (ret) {
+			dev_err(g0->dev, "Write failed %d\n", ret);
+			goto fw_release;
+		}
+		addr += size;
+		data += size;
+	}
+
+	dev_dbg(g0->dev, "Configure to boot from main flash\n");
+
+	ret = ucsi_stm32g0_bl_read(g0->ucsi, STM32G0_USER_OPTION_BYTES, &ob, sizeof(ob));
+	if (ret) {
+		dev_err(g0->dev, "read user option bytes failed %d\n", ret);
+		goto fw_release;
+	}
+
+	dev_dbg(g0->dev, "STM32G0_USER_OPTION_BYTES 0x%08x\n", ob);
+
+	/* Configure user option bytes to boot from main flash next time */
+	ob |= STM32G0_USER_OB_BOOT_MAIN;
+
+	/* Writing option bytes will also reset G0 for updates to be loaded */
+	ret = ucsi_stm32g0_bl_write(g0->ucsi, STM32G0_USER_OPTION_BYTES, &ob, sizeof(ob));
+	if (ret) {
+		dev_err(g0->dev, "write user option bytes failed %d\n", ret);
+		goto fw_release;
+	}
+
+	dev_info(g0->dev, "Starting, option bytes:0x%08x\n", ob);
+
+	/* STM32G0 FW boot delay */
+	msleep(500);
+
+	/* Register UCSI interface */
+	if (!ucsi_stm32g0_register(g0->ucsi))
+		g0->in_bootloader = false;
+
+fw_release:
+	release_firmware(fw);
+}
+
+static int ucsi_stm32g0_probe_bootloader(struct ucsi *ucsi)
+{
+	struct ucsi_stm32g0 *g0 = ucsi_get_drvdata(ucsi);
+	int ret;
+	u16 ucsi_version;
+
+	/* firmware-name is optional */
+	if (device_property_present(g0->dev, "firmware-name")) {
+		ret = device_property_read_string(g0->dev, "firmware-name", &g0->fw_name);
+		if (ret < 0)
+			return dev_err_probe(g0->dev, ret, "Error reading firmware-name\n");
+	}
+
+	if (g0->fw_name) {
+		/* STM32G0 in bootloader mode communicates at reserved address 0x51 */
+		g0->i2c_bl = i2c_new_dummy_device(g0->client->adapter, STM32G0_I2C_BL_ADDR);
+		if (IS_ERR(g0->i2c_bl)) {
+			ret = dev_err_probe(g0->dev, PTR_ERR(g0->i2c_bl),
+					    "Failed to register booloader I2C address\n");
+			return ret;
+		}
+	}
+
+	/*
+	 * Try to guess if the STM32G0 is running a UCSI firmware. First probe the UCSI FW at its
+	 * i2c address. Fallback to bootloader i2c address only if firmware-name is specified.
+	 */
+	ret = ucsi_stm32g0_read(ucsi, UCSI_VERSION, &ucsi_version, sizeof(ucsi_version));
+	if (!ret || !g0->fw_name)
+		return ret;
+
+	/* Speculatively read the bootloader version that has a known length. */
+	ret = ucsi_stm32g0_bl_get_version(ucsi, &g0->bl_version);
+	if (ret < 0) {
+		i2c_unregister_device(g0->i2c_bl);
+		return ret;
+	}
+
+	/* Device in bootloader mode */
+	g0->in_bootloader = true;
+	dev_info(g0->dev, "Bootloader Version 0x%02x\n", g0->bl_version);
+
+	return 0;
+}
+
 static int ucsi_stm32g0_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
@@ -154,24 +642,41 @@ static int ucsi_stm32g0_probe(struct i2c_client *client, const struct i2c_device
 
 	ucsi_set_drvdata(g0->ucsi, g0);
 
-	/* Request alert interrupt */
-	ret = request_threaded_irq(client->irq, NULL, ucsi_stm32g0_irq_handler, IRQF_ONESHOT,
-				   dev_name(&client->dev), g0);
-	if (ret) {
-		dev_err_probe(dev, ret, "request IRQ failed\n");
+	ret = ucsi_stm32g0_probe_bootloader(g0->ucsi);
+	if (ret < 0)
 		goto destroy;
+
+	/*
+	 * Don't register in bootloader mode: wait for the firmware to be loaded and started before
+	 * registering UCSI device.
+	 */
+	if (!g0->in_bootloader) {
+		ret = ucsi_stm32g0_register(g0->ucsi);
+		if (ret < 0)
+			goto freei2c;
 	}
 
-	ret = ucsi_register(g0->ucsi);
-	if (ret) {
-		dev_err_probe(dev, ret, "ucsi_register failed\n");
-		goto freeirq;
+	if (g0->fw_name) {
+		/*
+		 * Asynchronously flash (e.g. bootloader mode) or update the running firmware,
+		 * not to hang the boot process
+		 */
+		ret = request_firmware_nowait(THIS_MODULE, FW_ACTION_UEVENT, g0->fw_name, g0->dev,
+					      GFP_KERNEL, g0->ucsi, ucsi_stm32g0_fw_cb);
+		if (ret < 0) {
+			dev_err_probe(dev, ret, "firmware request failed\n");
+			goto unregister;
+		}
 	}
 
 	return 0;
 
-freeirq:
-	free_irq(client->irq, g0);
+unregister:
+	if (!g0->in_bootloader)
+		ucsi_stm32g0_unregister(g0->ucsi);
+freei2c:
+	if (g0->fw_name)
+		i2c_unregister_device(g0->i2c_bl);
 destroy:
 	ucsi_destroy(g0->ucsi);
 
@@ -182,8 +687,10 @@ static int ucsi_stm32g0_remove(struct i2c_client *client)
 {
 	struct ucsi_stm32g0 *g0 = i2c_get_clientdata(client);
 
-	ucsi_unregister(g0->ucsi);
-	free_irq(client->irq, g0);
+	if (!g0->in_bootloader)
+		ucsi_stm32g0_unregister(g0->ucsi);
+	if (g0->fw_name)
+		i2c_unregister_device(g0->i2c_bl);
 	ucsi_destroy(g0->ucsi);
 
 	return 0;
-- 
2.25.1