[PATCH v1] tpm_crb: Convert ACPI driver to a platform one

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>

In all cases in which a struct acpi_driver is used for binding a driver
to an ACPI device object, a corresponding platform device is created by
the ACPI core and that device is regarded as a proper representation of
underlying hardware.  Accordingly, a struct platform_driver should be
used by driver code to bind to that device.  There are multiple reasons
why drivers should not bind directly to ACPI device objects [1].

Overall, it is better to bind drivers to platform devices than to their
ACPI companions, so convert the tpm_crb ACPI driver to a platform one.

While this is not expected to alter functionality, it changes sysfs
layout and so it will be visible to user space.

Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 drivers/char/tpm/tpm_crb.c | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 6c25305c256e..7d1377e8e616 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -15,6 +15,7 @@
 #include <linux/highmem.h>
 #include <linux/rculist.h>
 #include <linux/module.h>
+#include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #ifdef CONFIG_ARM64
 #include <linux/arm-smccc.h>
@@ -602,13 +603,13 @@ static u64 crb_fixup_cmd_size(struct device *dev, struct resource *io_res,
 	return io_res->end - start + 1;
 }
 
-static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
+static int crb_map_io(struct device *dev, struct crb_priv *priv,
 		      struct acpi_table_tpm2 *buf)
 {
+	struct acpi_device *device = ACPI_COMPANION(dev);
 	struct list_head acpi_resource_list;
 	struct resource iores_array[TPM_CRB_MAX_RESOURCES + 1] = { {0} };
 	void __iomem *iobase_array[TPM_CRB_MAX_RESOURCES] = {NULL};
-	struct device *dev = &device->dev;
 	struct resource *iores;
 	void __iomem **iobase_ptr;
 	int i;
@@ -782,12 +783,13 @@ static int crb_map_pluton(struct device *dev, struct crb_priv *priv,
 	return 0;
 }
 
-static int crb_acpi_add(struct acpi_device *device)
+static int crb_acpi_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
+	struct acpi_device *device = ACPI_COMPANION(dev);
 	struct acpi_table_tpm2 *buf;
 	struct crb_priv *priv;
 	struct tpm_chip *chip;
-	struct device *dev = &device->dev;
 	struct tpm2_crb_smc *crb_smc;
 	struct tpm2_crb_ffa *crb_ffa;
 	struct tpm2_crb_pluton *crb_pluton;
@@ -867,7 +869,7 @@ static int crb_acpi_add(struct acpi_device *device)
 	priv->sm = sm;
 	priv->hid = acpi_device_hid(device);
 
-	rc = crb_map_io(device, priv, buf);
+	rc = crb_map_io(dev, priv, buf);
 	if (rc)
 		goto out;
 
@@ -901,12 +903,9 @@ static int crb_acpi_add(struct acpi_device *device)
 	return rc;
 }
 
-static void crb_acpi_remove(struct acpi_device *device)
+static void crb_acpi_remove(struct platform_device *pdev)
 {
-	struct device *dev = &device->dev;
-	struct tpm_chip *chip = dev_get_drvdata(dev);
-
-	tpm_chip_unregister(chip);
+	tpm_chip_unregister(platform_get_drvdata(pdev));
 }
 
 static const struct dev_pm_ops crb_pm = {
@@ -919,19 +918,17 @@ static const struct acpi_device_id crb_device_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, crb_device_ids);
 
-static struct acpi_driver crb_acpi_driver = {
-	.name = "tpm_crb",
-	.ids = crb_device_ids,
-	.ops = {
-		.add = crb_acpi_add,
-		.remove = crb_acpi_remove,
-	},
-	.drv = {
+static struct platform_driver crb_acpi_driver = {
+	.probe = crb_acpi_probe,
+	.remove = crb_acpi_remove,
+	.driver = {
+		.name = "tpm_crb_acpi",
+		.acpi_match_table = crb_device_ids,
 		.pm = &crb_pm,
 	},
 };
 
-module_acpi_driver(crb_acpi_driver);
+module_platform_driver(crb_acpi_driver);
 MODULE_AUTHOR("Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>");
 MODULE_DESCRIPTION("TPM2 Driver");
 MODULE_VERSION("0.1");
-- 
2.51.0