Add command line flag -F for frame length

Some I2C interface have limitation on the maximum
length of frame, either in RX and/or in TX.
While this could be automatically detected (how ?)
let's play easy and pass it from command line.

There is no use of these values yet.

Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>

Author: borneoa

main.c

@@ -52,6 +52,8 @@ struct port_options port_opts = {
 	.baudRate		= SERIAL_BAUD_57600,
 	.serial_mode		= "8e1",
 	.bus_addr		= 0,
+	.rx_frame_max		= STM32_MAX_RX_FRAME,
+	.tx_frame_max		= STM32_MAX_TX_FRAME,
 };
 int		rd	 	= 0;
 int		wr		= 0;
@@ -479,9 +481,12 @@ int main(int argc, char* argv[]) {
 	return ret;
 }
 
-int parse_options(int argc, char *argv[]) {
+int parse_options(int argc, char *argv[])
+{
 	int c;
-	while ((c = getopt(argc, argv, "a:b:m:r:w:e:vn:g:jkfcChuos:S:i:R")) != -1) {
+	char *pLen;
+
+	while ((c = getopt(argc, argv, "a:b:m:r:w:e:vn:g:jkfcChuos:S:F:i:R")) != -1) {
 		switch(c) {
 			case 'a':
 				port_opts.bus_addr = strtoul(optarg, NULL, 0);
@@ -595,7 +600,6 @@ int parse_options(int argc, char *argv[]) {
 					fprintf(stderr, "ERROR: Invalid options, can't specify start page / num pages and start address/length\n");
 					return 1;
 				} else {
-					char *pLen;
 					start_addr = strtoul(optarg, &pLen, 0);
 					if (*pLen == ':') {
 						pLen++;
@@ -607,6 +611,36 @@ int parse_options(int argc, char *argv[]) {
 					}
 				}
 				break;
+			case 'F':
+				port_opts.rx_frame_max = strtoul(optarg, &pLen, 0);
+				if (*pLen == ':') {
+					pLen++;
+					port_opts.tx_frame_max = strtoul(pLen, NULL, 0);
+				}
+				if (port_opts.rx_frame_max < 0
+				    || port_opts.tx_frame_max < 0) {
+					fprintf(stderr, "ERROR: Invalid negative value for option -F\n");
+					return 1;
+				}
+				if (port_opts.rx_frame_max == 0)
+					port_opts.rx_frame_max = STM32_MAX_RX_FRAME;
+				if (port_opts.tx_frame_max == 0)
+					port_opts.tx_frame_max = STM32_MAX_TX_FRAME;
+				if (port_opts.rx_frame_max < 20
+				    || port_opts.tx_frame_max < 5) {
+					fprintf(stderr, "ERROR: current code cannot work with small frames.\n");
+					fprintf(stderr, "min(RX) = 20, min(TX) = 5\n");
+					return 1;
+				}
+				if (port_opts.rx_frame_max > STM32_MAX_RX_FRAME) {
+					fprintf(stderr, "WARNING: Ignore RX length in option -F\n");
+					port_opts.rx_frame_max = STM32_MAX_RX_FRAME;
+				}
+				if (port_opts.tx_frame_max > STM32_MAX_TX_FRAME) {
+					fprintf(stderr, "WARNING: Ignore TX length in option -F\n");
+					port_opts.tx_frame_max = STM32_MAX_TX_FRAME;
+				}
+				break;
 			case 'f':
 				force_binary = 1;
 				break;
@@ -676,6 +710,7 @@ void show_help(char *name) {
 		"	-g address	Start execution at specified address (0 = flash start)\n"
 		"	-S address[:length]	Specify start address and optionally length for\n"
 		"	                   	read/write/erase operations\n"
+		"	-F RX_length[:TX_length]  Specify the max length of RX and TX frame\n"
 		"	-s start_page	Flash at specified page (0 = flash start)\n"
 		"	-f		Force binary parser\n"
 		"	-h		Show this help\n"

port.h

@@ -41,6 +41,8 @@ struct port_options {
 	serial_baud_t baudRate;
 	const char *serial_mode;
 	int bus_addr;
+	int rx_frame_max;
+	int tx_frame_max;
 };
 
 /*

stm32.h

@@ -24,6 +24,9 @@
 #include <stdint.h>
 #include "serial.h"
 
+#define STM32_MAX_RX_FRAME	256	/* cmd read memory */
+#define STM32_MAX_TX_FRAME	(1 + 256 + 1)	/* cmd write memory */
+
 typedef enum {
 	STM32_ERR_OK = 0,
 	STM32_ERR_UNKNOWN,	/* Generic error */

stm32flash.1

@@ -23,7 +23,9 @@ stm32flash \- flashing utility for STM32 and STM32W through UART or I2C
 .RB [ \-s
 .IR start_page ]
 .RB [ \-S
-.IR address [: length ]
+.IR address [: length ]]
+.RB [ \-F
+.IR RX_length [: TX_length ]]
 .RB [ \-i
 .IR GPIO_string ]
 .RI [ tty_device
@@ -140,6 +142,14 @@ Specify flash page offset (0 = flash start).
 .BI "\-S" " address" "[:" "length" "]"
 Specify start address and optionally length for read/write/erase/crc operations.
 
+.TP
+.BI "\-F" " RX_length" "[:" "TX_length" "]"
+Specify the maximum frame size for the current interface.
+Due to STM32 bootloader protocol, host will never handle frames bigger than
+256 byte in RX or 258 byte in TX.
+Due to current code, lowest limit in RX is 20 byte (to read a complete reply
+of command GET). Minimum limit in TX is 5 byte, required by protocol.
+
 .TP
 .B \-f
 Force binary parser while reading file with