i2c: add warning if failure on i2c clock stretching

borneoa · borneoa · commit ae96dba17721 · 2014-09-16T16:20:01.000+08:00
Bootloader v1.0 for i2c only implements host "wait" through
i2c "clock stretching".
Some i2c host controller could timeout after just few ms of
clock stretching. Since the i2c transaction cannot be retryed,
stm32flash can only quit.
Detect this case and rise a warning to the user.

Add document to better explain the issue.

Signed-off-by: Antonio Borneo &lt;borneo.antonio@gmail.com&gt;
diff --git a/i2c.c b/i2c.c
@@ -176,7 +176,7 @@ static struct varlen_cmd i2c_cmd_get_reply[] = {
 
 struct port_interface port_i2c = {
 	.name	= "i2c",
-	.flags	= 0,
+	.flags	= PORT_STRETCH_W,
 	.open	= i2c_open,
 	.close	= i2c_close,
 	.read	= i2c_read,
diff --git a/port.h b/port.h
@@ -33,6 +33,7 @@ typedef enum {
 #define PORT_GVR_ETX	(1 << 1)	/* cmd GVR returns protection status */
 #define PORT_CMD_INIT	(1 << 2)	/* use INIT cmd to autodetect speed */
 #define PORT_RETRY	(1 << 3)	/* allowed read() retry after timeout */
+#define PORT_STRETCH_W	(1 << 4)	/* warning for no-stretching commands */
 
 /* all options and flags used to open and configure an interface */
 struct port_options {
diff --git a/stm32.c b/stm32.c
@@ -94,6 +94,15 @@ static const uint32_t stm_reset_code_length = sizeof(stm_reset_code);
 
 extern const stm32_dev_t devices[];
 
+static void stm32_warn_stretching(const char *f)
+{
+	fprintf(stderr, "Attention !!!\n");
+	fprintf(stderr, "\tThis %s error could be caused by your I2C\n", f);
+	fprintf(stderr, "\tcontroller not accepting \"clock stretching\"\n");
+	fprintf(stderr, "\tas required by bootloader.\n");
+	fprintf(stderr, "\tCheck \"I2C.txt\" in stm32flash source code.\n");
+}
+
 static stm32_err_t stm32_get_ack_timeout(const stm32_t *stm, time_t timeout)
 {
 	struct port_interface *port = stm->port;
@@ -575,8 +584,12 @@ stm32_err_t stm32_write_memory(const stm32_t *stm, uint32_t address,
 		return STM32_ERR_UNKNOWN;
 
 	s_err = stm32_get_ack_timeout(stm, STM32_BLKWRITE_TIMEOUT);
-	if (s_err != STM32_ERR_OK)
+	if (s_err != STM32_ERR_OK) {
+		if (port->flags & PORT_STRETCH_W
+		    && stm->cmd->wm != STM32_CMD_WM_NS)
+			stm32_warn_stretching("write");
 		return STM32_ERR_UNKNOWN;
+	}
 	return STM32_ERR_OK;
 }
 
@@ -666,6 +679,9 @@ stm32_err_t stm32_erase_memory(const stm32_t *stm, uint8_t spage, uint8_t pages)
 			s_err = stm32_get_ack_timeout(stm, STM32_MASSERASE_TIMEOUT);
 			if (s_err != STM32_ERR_OK) {
 				fprintf(stderr, "Mass erase failed. Try specifying the number of pages to be erased.\n");
+				if (port->flags & PORT_STRETCH_W
+				    && stm->cmd->er != STM32_CMD_EE_NS)
+					stm32_warn_stretching("erase");
 				return STM32_ERR_UNKNOWN;
 			}
 			return STM32_ERR_OK;
@@ -708,6 +724,9 @@ stm32_err_t stm32_erase_memory(const stm32_t *stm, uint8_t spage, uint8_t pages)
 		s_err = stm32_get_ack_timeout(stm, STM32_SECTERASE_TIMEOUT);
 		if (s_err != STM32_ERR_OK) {
 			fprintf(stderr, "Page-by-page erase failed. Check the maximum pages your device supports.\n");
+			if (port->flags & PORT_STRETCH_W
+			    && stm->cmd->er != STM32_CMD_EE_NS)
+				stm32_warn_stretching("erase");
 			return STM32_ERR_UNKNOWN;
 		}
 
@@ -716,7 +735,13 @@ stm32_err_t stm32_erase_memory(const stm32_t *stm, uint8_t spage, uint8_t pages)
 
 	/* And now the regular erase (0x43) for all other chips */
 	if (pages == 0xFF) {
-		return stm32_send_command_timeout(stm, 0xFF, STM32_MASSERASE_TIMEOUT);
+		s_err = stm32_send_command_timeout(stm, 0xFF, STM32_MASSERASE_TIMEOUT);
+		if (s_err != STM32_ERR_OK) {
+			if (port->flags & PORT_STRETCH_W)
+				stm32_warn_stretching("erase");
+			return STM32_ERR_UNKNOWN;
+		}
+		return STM32_ERR_OK;
 	} else {
 		uint8_t cs = 0;
 		uint8_t pg_num;
@@ -741,8 +766,11 @@ stm32_err_t stm32_erase_memory(const stm32_t *stm, uint8_t spage, uint8_t pages)
 			return STM32_ERR_UNKNOWN;
 		}
 		s_err = stm32_get_ack_timeout(stm, STM32_MASSERASE_TIMEOUT);
-		if (s_err != STM32_ERR_OK)
+		if (s_err != STM32_ERR_OK) {
+			if (port->flags & PORT_STRETCH_W)
+				stm32_warn_stretching("erase");
 			return STM32_ERR_UNKNOWN;
+		}
 		return STM32_ERR_OK;
 	}
 }
