dummyflasher.c: Fix null par data and size param handling

This patch fixes a few bugs that two patches ( `3149822cd45cb2e5841e15d648783748ba1b2ec6` && `3b8fe0f8e907c0ba9f7c7935e950f3e1538d427f`) brought:
 * Check the presence of 'size' param only if the emulate is VARIABLE_SIZE.
 * Initialize 'flash->st->par.data' in dummy_init() so that it can probe the VARIABLE_SIZE emulator correct in probe_variable_size().
 * Replace atoi() with strtol().
 * Revise man page to describe how to use the VARIABLE_SIZE emulation target.

TEST:
$ flashrom -p dummy:image=dummy.bin,emulate=VARIABLE_SIZE,size=16777216 \
-w ${IMG} -V -f
...
Verifying flash... VERIFIED.
Writing dummy.bin

$ flashrom -p dummy:image=dummy.bin,emulate=VARIABLE_SIZE -w ${IMG} -V -f
...
dummy_init: the size parameter is not given.
Unhandled programmer parameters (possibly due to another failure): image=dummy.bin,
Error: Programmer initialization failed

$ flashrom -p dummy:image=dummy.bin,emulate=SST25VF040.REMS -c SST25LF040A -w ${IMG}
...
Erasing and writing flash chip... Erase/write done.
Verifying flash... VERIFIED.

$ man flashrom
...
 * Dummy vendor VARIABLE_SIZE SPI flash chip (configurable size, page write)

 Example: flashrom -p dummy:emulate=SST25VF040.REMS

 To use VARIABLE_SIZE chip, size must be specified to configure the size of the flash chip as a power of two.

 Example: flashrom -p dummy:emulate=VARIABLE_SIZE,size=16777216,image=dummy.bin
...

Signed-off-by: Namyoon Woo <namyoon@google.com>
Change-Id: Ie6481943a831b946a91b643b4d79e684c27e48b8
Reviewed-on: https://review.coreboot.org/c/flashrom/+/46536
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>

2 files changed, 20 insertions, 6 deletions

diff --git a/dummyflasher.c b/dummyflasher.c
index 32a00abb7..82aa3c8d9 100644
--- a/dummyflasher.c
+++ b/dummyflasher.c
@@ -126,7 +126,7 @@ static struct spi_master spi_master_dummyflasher = {
 	.write_aai	= default_spi_write_aai,
 };
 
-static const struct par_master par_master_dummy = {
+static struct par_master par_master_dummy = {
 		.chip_readb		= dummy_chip_readb,
 		.chip_readw		= dummy_chip_readw,
 		.chip_readl		= dummy_chip_readl,
@@ -166,7 +166,7 @@ int dummy_init(void)
 	unsigned int i;
 #if EMULATE_SPI_CHIP
 	char *status = NULL;
-	int size = -1;  /* size for VARIOUS_SIZE chip device */
+	int size = -1;  /* size for VARIABLE_SIZE chip device */
 #endif
 #if EMULATE_CHIP
 	struct stat image_stat;
@@ -180,6 +180,7 @@ int dummy_init(void)
 	data->emu_chip = EMULATE_NONE;
 	data->delay_us = 0;
 	spi_master_dummyflasher.data = data;
+	par_master_dummy.data = data;
 
 	msg_pspew("%s\n", __func__);
 
@@ -343,7 +344,7 @@ int dummy_init(void)
 #if EMULATE_SPI_CHIP
 	tmp = extract_programmer_param("size");
 	if (tmp) {
-		size = atoi(tmp);
+		size = strtol(tmp, NULL, 10);
 		if (size <= 0 || (size % 1024 != 0)) {
 			msg_perr("%s: Chip size is not a multipler of 1024: %s\n",
 					 __func__, tmp);
@@ -351,9 +352,6 @@ int dummy_init(void)
 			return 1;
 		}
 		free(tmp);
-	} else {
-		msg_perr("%s: the size parameter is not given.\n", __func__);
-		return 1;
 	}
 #endif
 
@@ -433,6 +431,11 @@ int dummy_init(void)
 	 *   flashrom -p dummy:emulate=VARIABLE_SIZE,size=4194304
 	 */
 	if (!strcmp(tmp, "VARIABLE_SIZE")) {
+		if (size == -1) {
+			msg_perr("%s: the size parameter is not given.\n", __func__);
+			free(tmp);
+			return 1;
+		}
 		data->emu_chip = EMULATE_VARIABLE_SIZE;
 		data->emu_chip_size = size;
 		data->emu_max_byteprogram_size = 256;
diff --git a/flashrom.8.tmpl b/flashrom.8.tmpl
index db50d5954..02f60dc9b 100644
--- a/flashrom.8.tmpl
+++ b/flashrom.8.tmpl
@@ -646,8 +646,19 @@ vendor):
 .sp
 .RB "* Macronix " MX25L6436 " SPI flash chip (8192 kB, RDID, SFDP)"
 .sp
+.RB "* Dummy vendor " VARIABLE_SIZE " SPI flash chip (configurable size, page write)"
+.sp
 Example:
 .B "flashrom -p dummy:emulate=SST25VF040.REMS"
+.sp
+To use
+.B VARIABLE_SIZE
+chip,
+.B size
+must be specified to configure the size of the flash chip as a power of two.
+.sp
+Example:
+.B "flashrom -p dummy:emulate=VARIABLE_SIZE,size=16777216,image=dummy.bin"
 .TP
 .B Persistent images
 .sp