staging: gpib: Avoid plain integers as NULL pointers

A number of drivers were comparing request_region() with 0,
others were passing 0 instead of NULL as a pointer argument.

This led to the following sparse warning, for example:

cb7210/cb7210.c:1043:72: warning: Using plain integer as NULL pointer

Use !request_region() to test for NULL return and use NULL instead
of 0 as pointer parameter.

Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20250114165403.16410-4-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gpib/cb7210/cb7210.c

@@ -1040,7 +1040,7 @@ int cb_isa_attach(gpib_board_t *board, const gpib_board_config_t *config)
 		return retval;
 	cb_priv = board->private_data;
 	nec_priv = &cb_priv->nec7210_priv;
-	if (request_region(config->ibbase, cb7210_iosize, "cb7210") == 0) {
+	if (!request_region(config->ibbase, cb7210_iosize, "cb7210")) {
 		pr_err("gpib: ioports starting at 0x%u are already in use\n", config->ibbase);
 		return -EIO;
 	}
@@ -1459,8 +1459,8 @@ int cb_pcmcia_attach(gpib_board_t *board, const gpib_board_config_t *config)
 	cb_priv = board->private_data;
 	nec_priv = &cb_priv->nec7210_priv;
 
-	if (request_region(curr_dev->resource[0]->start, resource_size(curr_dev->resource[0]),
-			   "cb7210") == 0)	{
+	if (!request_region(curr_dev->resource[0]->start, resource_size(curr_dev->resource[0]),
+			    "cb7210"))	{
 		pr_err("gpib: ioports starting at 0x%lx are already in use\n",
 		       (unsigned long)curr_dev->resource[0]->start);
 		return -EIO;

drivers/staging/gpib/common/gpib_os.c

@@ -2197,7 +2197,7 @@ static int __init gpib_common_init_module(void)
 		return PTR_ERR(gpib_class);
 	}
 	for (i = 0; i < GPIB_MAX_NUM_BOARDS; ++i)
-		board_array[i].gpib_dev = device_create(gpib_class, 0,
+		board_array[i].gpib_dev = device_create(gpib_class, NULL,
 							MKDEV(GPIB_CODE, i), NULL, "gpib%i", i);
 
 	return 0;

drivers/staging/gpib/common/iblib.c

@@ -695,7 +695,7 @@ int ibwait(gpib_board_t *board, int wait_mask, int clear_mask, int set_mask,
 
 	/* make sure we only clear status bits that we are reporting */
 	if (*status & clear_mask || set_mask)
-		general_ibstatus(board, status_queue, *status & clear_mask, set_mask, 0);
+		general_ibstatus(board, status_queue, *status & clear_mask, set_mask, NULL);
 
 	return 0;
 }

drivers/staging/gpib/gpio/gpib_bitbang.c

@@ -265,7 +265,7 @@ static struct gpiod_lookup_table gpib_gpio_table_0 = {
 static struct gpiod_lookup_table *lookup_tables[] = {
 	&gpib_gpio_table_0,
 	&gpib_gpio_table_1,
-	0
+	NULL
 };
 
 /* struct which defines private_data for gpio driver */
@@ -1119,7 +1119,7 @@ static void release_gpios(void)
 	for (j = 0 ; j < NUM_PINS ; j++) {
 		if (all_descriptors[j]) {
 			gpiod_put(all_descriptors[j]);
-			all_descriptors[j] = 0;
+			all_descriptors[j] = NULL;
 		}
 	}
 }

drivers/staging/gpib/ines/ines_gpib.c

@@ -1342,8 +1342,8 @@ int ines_common_pcmcia_attach(gpib_board_t *board)
 	ines_priv = board->private_data;
 	nec_priv = &ines_priv->nec7210_priv;
 
-	if (request_region(curr_dev->resource[0]->start,
-			   resource_size(curr_dev->resource[0]), "ines_gpib") == 0) {
+	if (!request_region(curr_dev->resource[0]->start,
+			    resource_size(curr_dev->resource[0]), "ines_gpib")) {
 		pr_err("ines_gpib: ioports at 0x%lx already in use\n",
 		       (unsigned long)(curr_dev->resource[0]->start));
 		return -1;

drivers/staging/gpib/pc2/pc2_gpib.c

@@ -426,7 +426,7 @@ int pc2_attach(gpib_board_t *board, const gpib_board_config_t *config)
 	nec_priv = &pc2_priv->nec7210_priv;
 	nec_priv->offset = pc2_reg_offset;
 
-	if (request_region(config->ibbase, pc2_iosize, "pc2") == 0) {
+	if (!request_region(config->ibbase, pc2_iosize, "pc2")) {
 		pr_err("gpib: ioports are already in use\n");
 		return -1;
 	}

drivers/staging/gpib/tnt4882/tnt4882_gpib.c

@@ -1896,8 +1896,8 @@ int ni_pcmcia_attach(gpib_board_t *board, const gpib_board_config_t *config)
 	nec_priv->offset = atgpib_reg_offset;
 
 	DEBUG(0, "ioport1 window attributes: 0x%lx\n", curr_dev->resource[0]->flags);
-	if (request_region(curr_dev->resource[0]->start, resource_size(curr_dev->resource[0]),
-			   "tnt4882") == 0) {
+	if (!request_region(curr_dev->resource[0]->start, resource_size(curr_dev->resource[0]),
+			    "tnt4882")) {
 		pr_err("gpib: ioports starting at 0x%lx are already in use\n",
 		       (unsigned long)curr_dev->resource[0]->start);
 		return -EIO;