driver core: Constify API device_find_child() and adapt for various usages

Constify the following API:
struct device *device_find_child(struct device *dev, void *data,
int (*match)(struct device *dev, void *data));
To :
struct device *device_find_child(struct device *dev, const void *data,
device_match_t match);
typedef int (*device_match_t)(struct device *dev, const void *data);
with the following reasons:

- Protect caller's match data @*data which is for comparison and lookup
and the API does not actually need to modify @*data.

- Make the API's parameters (@match)() and @data have the same type as
all of other device finding APIs (bus|class|driver)_find_device().

- All kinds of existing device match functions can be directly taken
as the API's argument, they were exported by driver core.

Constify the API and adapt for various existing usages.

BTW, various subsystem changes are squashed into this commit to meet
'git bisect' requirement, and this commit has the minimal and simplest
changes to complement squashing shortcoming, and that may bring extra
code improvement.

Reviewed-by: Alison Schofield <[e-mail]>
Reviewed-by: Takashi Sakamoto <[e-mail]>
Acked-by: Uwe Kleine-König <[e-mail]> # for drivers/pwm
Signed-off-by: Zijun Hu <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
Reviewed-by: Mathieu Poirier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

arch/sparc/kernel/vio.c

···
 	u64 node;
 };
 
-static int vio_md_node_match(struct device *dev, void *arg)
+static int vio_md_node_match(struct device *dev, const void *arg)
 {
 	struct vio_dev *vdev = to_vio_dev(dev);
-	struct vio_remove_node_data *node_data;
+	const struct vio_remove_node_data *node_data;
 	u64 node;
 
-	node_data = (struct vio_remove_node_data *)arg;
+	node_data = (const struct vio_remove_node_data *)arg;
 
 	node = vio_vdev_node(node_data->hp, vdev);
 

drivers/base/core.c

···
  *
  * NOTE: you will need to drop the reference with put_device() after use.
  */
-struct device *device_find_child(struct device *parent, void *data,
-				 int (*match)(struct device *dev, void *data))
+struct device *device_find_child(struct device *parent, const void *data,
+				 device_match_t match)
 {
 	struct klist_iter i;
 	struct device *child;
···
 }
 EXPORT_SYMBOL_GPL(device_find_child_by_name);
 
-static int match_any(struct device *dev, void *unused)
+static int match_any(struct device *dev, const void *unused)
 {
 	return 1;
 }

drivers/block/sunvdc.c

···
 	char	*type;
 };
 
-static int vdc_device_probed(struct device *dev, void *arg)
+static int vdc_device_probed(struct device *dev, const void *arg)
 {
 	struct vio_dev *vdev = to_vio_dev(dev);
-	struct vdc_check_port_data *port_data;
+	const struct vdc_check_port_data *port_data;
 
-	port_data = (struct vdc_check_port_data *)arg;
+	port_data = (const struct vdc_check_port_data *)arg;
 
 	if ((vdev->dev_no == port_data->dev_no) &&
 	    (!(strcmp((char *)&vdev->type, port_data->type))) &&

drivers/bus/fsl-mc/dprc-driver.c

···
 }
 EXPORT_SYMBOL_GPL(dprc_remove_devices);
 
-static int __fsl_mc_device_match(struct device *dev, void *data)
+static int __fsl_mc_device_match(struct device *dev, const void *data)
 {
-	struct fsl_mc_obj_desc *obj_desc = data;
+	const struct fsl_mc_obj_desc *obj_desc = data;
 	struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
 
 	return fsl_mc_device_match(mc_dev, obj_desc);

drivers/cxl/core/pci.c

···
 }
 
 /* require dvsec ranges to be covered by a locked platform window */
-static int dvsec_range_allowed(struct device *dev, void *arg)
+static int dvsec_range_allowed(struct device *dev, const void *arg)
 {
-	struct range *dev_range = arg;
+	const struct range *dev_range = arg;
 	struct cxl_decoder *cxld;
 
 	if (!is_root_decoder(dev))

drivers/cxl/core/pmem.c

···
 }
 EXPORT_SYMBOL_NS_GPL(is_cxl_nvdimm_bridge, "CXL");
 
-static int match_nvdimm_bridge(struct device *dev, void *data)
+static int match_nvdimm_bridge(struct device *dev, const void *data)
 {
 	return is_cxl_nvdimm_bridge(dev);
 }

drivers/cxl/core/region.c

···
 	return 0;
 }
 
-static int match_free_decoder(struct device *dev, void *data)
+static int match_free_decoder(struct device *dev, const void *data)
 {
 	struct cxl_port *port = to_cxl_port(dev->parent);
 	struct cxl_decoder *cxld;
···
 	return 1;
 }
 
-static int match_auto_decoder(struct device *dev, void *data)
+static int match_auto_decoder(struct device *dev, const void *data)
 {
-	struct cxl_region_params *p = data;
+	const struct cxl_region_params *p = data;
 	struct cxl_decoder *cxld;
 	struct range *r;
 
···
 	return port->parent_dport->port;
 }
 
-static int match_switch_decoder_by_range(struct device *dev, void *data)
+static int match_switch_decoder_by_range(struct device *dev,
+					 const void *data)
 {
 	struct cxl_switch_decoder *cxlsd;
-	struct range *r1, *r2 = data;
+	const struct range *r1, *r2 = data;
+
 
 	if (!is_switch_decoder(dev))
 		return 0;
···
 	return rc;
 }
 
-static int match_root_decoder_by_range(struct device *dev, void *data)
+static int match_root_decoder_by_range(struct device *dev,
+				       const void *data)
 {
-	struct range *r1, *r2 = data;
+	const struct range *r1, *r2 = data;
 	struct cxl_root_decoder *cxlrd;
 
 	if (!is_root_decoder(dev))
···
 	return range_contains(r1, r2);
 }
 
-static int match_region_by_range(struct device *dev, void *data)
+static int match_region_by_range(struct device *dev, const void *data)
 {
 	struct cxl_region_params *p;
 	struct cxl_region *cxlr;
-	struct range *r = data;
+	const struct range *r = data;
 	int rc = 0;
 
 	if (!is_cxl_region(dev))

drivers/firewire/core-device.c

···
 	return 0;
 }
 
-static int compare_configuration_rom(struct device *dev, void *data)
+static int compare_configuration_rom(struct device *dev, const void *data)
 {
 	const struct fw_device *old = fw_device(dev);
 	const u32 *config_rom = data;
···
 	//
 	// serialize config_rom access.
 	scoped_guard(rwsem_read, &fw_device_rwsem) {
-		found = device_find_child(card->device, (void *)device->config_rom,
+		found = device_find_child(card->device, device->config_rom,
 					  compare_configuration_rom);
 	}
 	if (found) {

drivers/firmware/arm_scmi/bus.c

···
 	return 0;
 }
 
-static int scmi_match_by_id_table(struct device *dev, void *data)
+static int scmi_match_by_id_table(struct device *dev, const void *data)
 {
 	struct scmi_device *sdev = to_scmi_dev(dev);
-	struct scmi_device_id *id_table = data;
+	const struct scmi_device_id *id_table = data;
 
 	return sdev->protocol_id == id_table->protocol_id &&
 		(id_table->name && !strcmp(sdev->name, id_table->name));

drivers/firmware/efi/dev-path-parser.c

···
 	return 0;
 }
 
-static int __init match_pci_dev(struct device *dev, void *data)
+static int __init match_pci_dev(struct device *dev, const void *data)
 {
-	unsigned int devfn = *(unsigned int *)data;
+	unsigned int devfn = *(const unsigned int *)data;
 
 	return dev_is_pci(dev) && to_pci_dev(dev)->devfn == devfn;
 }

drivers/gpio/gpio-sim.c

···
 	return devm_add_action_or_reset(dev, gpio_sim_sysfs_remove, chip);
 }
 
-static int gpio_sim_dev_match_fwnode(struct device *dev, void *data)
+static int gpio_sim_dev_match_fwnode(struct device *dev, const void *data)
 {
 	return device_match_fwnode(dev, data);
 }

drivers/gpu/drm/mediatek/mtk_drm_drv.c

···
 };
 MODULE_DEVICE_TABLE(of, mtk_drm_of_ids);
 
-static int mtk_drm_match(struct device *dev, void *data)
+static int mtk_drm_match(struct device *dev, const void *data)
 {
 	if (!strncmp(dev_name(dev), "mediatek-drm", sizeof("mediatek-drm") - 1))
 		return true;

drivers/hwmon/hwmon.c

···
 
 static DEFINE_MUTEX(hwmon_pec_mutex);
 
-static int hwmon_match_device(struct device *dev, void *data)
+static int hwmon_match_device(struct device *dev, const void *data)
 {
 	return dev->class == &hwmon_class;
 }

drivers/media/pci/mgb4/mgb4_core.c

···
 };
 #endif
 
-static int match_i2c_adap(struct device *dev, void *data)
+static int match_i2c_adap(struct device *dev, const void *data)
 {
 	return i2c_verify_adapter(dev) ? 1 : 0;
 }
···
 	return dev ? to_i2c_adapter(dev) : NULL;
 }
 
-static int match_spi_adap(struct device *dev, void *data)
+static int match_spi_adap(struct device *dev, const void *data)
 {
 	return to_spi_device(dev) ? 1 : 0;
 }

drivers/nvdimm/bus.c

···
 	DIMM_IOCTL,
 };
 
-static int match_dimm(struct device *dev, void *data)
+static int match_dimm(struct device *dev, const void *data)
 {
 	long id = (long) data;
 

drivers/pwm/core.c

···
 	return 0;
 }
 
-static int pwm_unexport_match(struct device *pwm_dev, void *data)
+static int pwm_unexport_match(struct device *pwm_dev, const void *data)
 {
 	return pwm_from_dev(pwm_dev) == data;
 }

drivers/rpmsg/rpmsg_core.c

···
  * this is used to make sure we're not creating rpmsg devices for channels
  * that already exist.
  */
-static int rpmsg_device_match(struct device *dev, void *data)
+static int rpmsg_device_match(struct device *dev, const void *data)
 {
-	struct rpmsg_channel_info *chinfo = data;
+	const struct rpmsg_channel_info *chinfo = data;
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 
 	if (chinfo->src != RPMSG_ADDR_ANY && chinfo->src != rpdev->src)

drivers/scsi/qla4xxx/ql4_os.c

···
  *	1: if flashnode entry is non-persistent
  *	0: if flashnode entry is persistent
  **/
-static int qla4xxx_sysfs_ddb_is_non_persistent(struct device *dev, void *data)
+static int qla4xxx_sysfs_ddb_is_non_persistent(struct device *dev,
+					       const void *data)
 {
 	struct iscsi_bus_flash_session *fnode_sess;
 

drivers/scsi/scsi_transport_iscsi.c

···
  *  1 on success
  *  0 on failure
  */
-static int iscsi_is_flashnode_conn_dev(struct device *dev, void *data)
+static int iscsi_is_flashnode_conn_dev(struct device *dev, const void *data)
 {
 	return dev->bus == &iscsi_flashnode_bus;
 }
···
 	return 0;
 }
 
-static int flashnode_match_index(struct device *dev, void *data)
+static int flashnode_match_index(struct device *dev, const void *data)
 {
 	struct iscsi_bus_flash_session *fnode_sess = NULL;
 	int ret = 0;
···
 		goto exit_match_index;
 
 	fnode_sess = iscsi_dev_to_flash_session(dev);
-	ret = (fnode_sess->target_id == *((int *)data)) ? 1 : 0;
+	ret = (fnode_sess->target_id == *((const int *)data)) ? 1 : 0;
 
 exit_match_index:
 	return ret;
···
  *  %NULL on failure
  */
 struct device *
-iscsi_find_flashnode_sess(struct Scsi_Host *shost, void *data,
-			  int (*fn)(struct device *dev, void *data))
+iscsi_find_flashnode_sess(struct Scsi_Host *shost, const void *data,
+			  device_match_t fn)
 {
 	return device_find_child(&shost->shost_gendev, data, fn);
 }

drivers/slimbus/core.c

···
 		a->instance == b->instance);
 }
 
-static int slim_match_dev(struct device *dev, void *data)
+static int slim_match_dev(struct device *dev, const void *data)
 {
-	struct slim_eaddr *e_addr = data;
+	const struct slim_eaddr *e_addr = data;
 	struct slim_device *sbdev = to_slim_device(dev);
 
 	return slim_eaddr_equal(&sbdev->e_addr, e_addr);
···
 }
 EXPORT_SYMBOL_GPL(slim_get_device);
 
-static int of_slim_match_dev(struct device *dev, void *data)
+static int of_slim_match_dev(struct device *dev, const void *data)
 {
-	struct device_node *np = data;
+	const struct device_node *np = data;
 	struct slim_device *sbdev = to_slim_device(dev);
 
 	return (sbdev->dev.of_node == np);

drivers/thunderbolt/retimer.c

···
 	u8 index;
 };
 
-static int retimer_match(struct device *dev, void *data)
+static int retimer_match(struct device *dev, const void *data)
 {
 	const struct tb_retimer_lookup *lookup = data;
 	struct tb_retimer *rt = tb_to_retimer(dev);

drivers/thunderbolt/xdomain.c

···
 	return 0;
 }
 
-static int find_service(struct device *dev, void *data)
+static int find_service(struct device *dev, const void *data)
 {
 	const struct tb_property *p = data;
 	struct tb_service *svc;

drivers/tty/serial/serial_core.c

···
 	struct uart_driver *driver;
 };
 
-static int serial_match_port(struct device *dev, void *data)
+static int serial_match_port(struct device *dev, const void *data)
 {
-	struct uart_match *match = data;
+	const struct uart_match *match = data;
 	struct tty_driver *tty_drv = match->driver->tty_driver;
 	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
 		match->port->line;

drivers/usb/typec/class.c

···
 /* ------------------------------------------------------------------------- */
 /* Alternate Modes */
 
-static int altmode_match(struct device *dev, void *data)
+static int altmode_match(struct device *dev, const void *data)
 {
 	struct typec_altmode *adev = to_typec_altmode(dev);
-	struct typec_device_id *id = data;
+	const struct typec_device_id *id = data;
 
 	if (!is_typec_altmode(dev))
 		return 0;
···
 	.release = typec_cable_release,
 };
 
-static int cable_match(struct device *dev, void *data)
+static int cable_match(struct device *dev, const void *data)
 {
 	return is_typec_cable(dev);
 }
···
 /* --------------------------------------- */
 /* Driver callbacks to report role updates */
 
-static int partner_match(struct device *dev, void *data)
+static int partner_match(struct device *dev, const void *data)
 {
 	return is_typec_partner(dev);
 }

include/linux/device.h

···
 int device_for_each_child_reverse_from(struct device *parent,
 				       struct device *from, const void *data,
 				       int (*fn)(struct device *, const void *));
-struct device *device_find_child(struct device *dev, void *data,
-				 int (*match)(struct device *dev, void *data));
+struct device *device_find_child(struct device *dev, const void *data,
+				 device_match_t match);
 struct device *device_find_child_by_name(struct device *parent,
 					 const char *name);
 struct device *device_find_any_child(struct device *parent);

include/scsi/scsi_transport_iscsi.h

···
 extern int iscsi_flashnode_bus_match(struct device *dev,
 				     const struct device_driver *drv);
 extern struct device *
-iscsi_find_flashnode_sess(struct Scsi_Host *shost, void *data,
-			  int (*fn)(struct device *dev, void *data));
+iscsi_find_flashnode_sess(struct Scsi_Host *shost, const void *data,
+			  device_match_t fn);
 extern struct device *
 iscsi_find_flashnode_conn(struct iscsi_bus_flash_session *fnode_sess);
 

net/dsa/dsa.c

···
 	return dsa_switch_parse_ports_of(ds, dn);
 }
 
-static int dev_is_class(struct device *dev, void *class)
+static int dev_is_class(struct device *dev, const void *class)
 {
 	if (dev->class != NULL && !strcmp(dev->class->name, class))
 		return 1;

tools/testing/cxl/test/cxl.c

···
 	cxld->reset = mock_decoder_reset;
 }
 
-static int first_decoder(struct device *dev, void *data)
+static int first_decoder(struct device *dev, const void *data)
 {
 	struct cxl_decoder *cxld;