ACPI: x86: cmos_rtc: Clean up address space handler driver

Make multiple changes that do not alter functionality to the CMOS RTC
ACPI address space handler driver, including the following:

 - Drop the unused .detach() callback from cmos_rtc_handler.

 - Rename acpi_cmos_rtc_attach_handler() to acpi_cmos_rtc_attach().

 - Rearrange acpi_cmos_rtc_space_handler() to reduce the number of
   redundant checks and make white space follow the coding style.

 - Adjust an error message in acpi_install_cmos_rtc_space_handler()
   and make the white space follow the coding style.

 - Rearrange acpi_remove_cmos_rtc_space_handler() and adjust an error
   message in it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/5094429.31r3eYUQgx@rafael.j.wysocki

Author: rafaeljw

drivers/acpi/x86/cmos_rtc.c

@@ -24,43 +24,47 @@ static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
 	{}
 };
 
-static acpi_status
-acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address,
-		      u32 bits, u64 *value64,
-		      void *handler_context, void *region_context)
+static acpi_status acpi_cmos_rtc_space_handler(u32 function,
+					       acpi_physical_address address,
+					       u32 bits, u64 *value64,
+					       void *handler_context,
+					       void *region_context)
 {
-	int i;
+	unsigned int i, bytes = DIV_ROUND_UP(bits, 8);
 	u8 *value = (u8 *)value64;
 
 	if (address > 0xff || !value64)
 		return AE_BAD_PARAMETER;
 
-	if (function != ACPI_WRITE && function != ACPI_READ)
-		return AE_BAD_PARAMETER;
+	guard(spinlock_irq)(&rtc_lock);
+
+	if (function == ACPI_WRITE) {
+		for (i = 0; i < bytes; i++, address++, value++)
+			CMOS_WRITE(*value, address);
 
-	spin_lock_irq(&rtc_lock);
+		return AE_OK;
+	}
 
-	for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value)
-		if (function == ACPI_READ)
+	if (function == ACPI_READ) {
+		for (i = 0; i < bytes; i++, address++, value++)
 			*value = CMOS_READ(address);
-		else
-			CMOS_WRITE(*value, address);
 
-	spin_unlock_irq(&rtc_lock);
+		return AE_OK;
+	}
 
-	return AE_OK;
+	return AE_BAD_PARAMETER;
 }
 
 int acpi_install_cmos_rtc_space_handler(acpi_handle handle)
 {
 	acpi_status status;
 
 	status = acpi_install_address_space_handler(handle,
-			ACPI_ADR_SPACE_CMOS,
-			&acpi_cmos_rtc_space_handler,
-			NULL, NULL);
+						    ACPI_ADR_SPACE_CMOS,
+						    acpi_cmos_rtc_space_handler,
+						    NULL, NULL);
 	if (ACPI_FAILURE(status)) {
-		pr_err("Error installing CMOS-RTC region handler\n");
+		pr_err("Failed to install CMOS-RTC address space handler\n");
 		return -ENODEV;
 	}
 
@@ -70,26 +74,25 @@ EXPORT_SYMBOL_GPL(acpi_install_cmos_rtc_space_handler);
 
 void acpi_remove_cmos_rtc_space_handler(acpi_handle handle)
 {
-	if (ACPI_FAILURE(acpi_remove_address_space_handler(handle,
-			ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
-		pr_err("Error removing CMOS-RTC region handler\n");
+	acpi_status status;
+
+	status = acpi_remove_address_space_handler(handle,
+						   ACPI_ADR_SPACE_CMOS,
+						   acpi_cmos_rtc_space_handler);
+	if (ACPI_FAILURE(status))
+		pr_err("Failed to remove CMOS-RTC address space handler\n");
 }
 EXPORT_SYMBOL_GPL(acpi_remove_cmos_rtc_space_handler);
 
-static int acpi_cmos_rtc_attach_handler(struct acpi_device *adev, const struct acpi_device_id *id)
+static int acpi_cmos_rtc_attach(struct acpi_device *adev,
+				const struct acpi_device_id *id)
 {
 	return acpi_install_cmos_rtc_space_handler(adev->handle);
 }
 
-static void acpi_cmos_rtc_detach_handler(struct acpi_device *adev)
-{
-	acpi_remove_cmos_rtc_space_handler(adev->handle);
-}
-
 static struct acpi_scan_handler cmos_rtc_handler = {
 	.ids = acpi_cmos_rtc_ids,
-	.attach = acpi_cmos_rtc_attach_handler,
-	.detach = acpi_cmos_rtc_detach_handler,
+	.attach = acpi_cmos_rtc_attach,
 };
 
 void __init acpi_cmos_rtc_init(void)