[PATCH v2 8/9] i2c: designware: Add doorbell support for Skyrim

[Mario Limonciello <mario.limonciello@amd.com>]

Skyrim doesn't use the platform feature mailbox for communication
for I2C arbitration, it relies upon ringing a doorbell.

Add a new ACPI ID to use for Skyrim and when that ID is detected
use the doorbell instead.

Link: https://lore.kernel.org/linux-i2c/20220916131854.687371-3-jsd@semihalf.com/
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v1->v2:
 * New patch
Note: This ACPI ID hasn't currently been reserved, but as Skyrim runs coreboot
it should be easy enough to modify the BIOS and test it out.
If this approach works and has general agreement it can be reserved.
---
 drivers/i2c/busses/i2c-designware-amdpsp.c  | 29 ++++++++++++++-------
 drivers/i2c/busses/i2c-designware-platdrv.c |  1 +
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-amdpsp.c b/drivers/i2c/busses/i2c-designware-amdpsp.c
index 105584abcf8f..e1a4d3002c80 100644
--- a/drivers/i2c/busses/i2c-designware-amdpsp.c
+++ b/drivers/i2c/busses/i2c-designware-amdpsp.c
@@ -73,34 +73,44 @@ static int psp_send_check_i2c_req(struct psp_i2c_req *req)
 	return check_i2c_req_sts(req);
 }
 
-static int psp_send_i2c_req(enum psp_i2c_req_type i2c_req_type)
+static int psp_send_i2c_req_amdi0019(enum psp_i2c_req_type i2c_req_type)
 {
 	struct psp_i2c_req *req;
-	unsigned long start;
 	int status, ret;
 
 	/* Allocate command-response buffer */
 	req = kzalloc(sizeof(*req), GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
-
 	req->hdr.payload_size = sizeof(*req);
 	req->type = i2c_req_type;
-
-	start = jiffies;
 	ret = read_poll_timeout(psp_send_check_i2c_req, status,
 				(status != -EBUSY),
 				PSP_I2C_REQ_RETRY_DELAY_US,
 				PSP_I2C_REQ_RETRY_CNT * PSP_I2C_REQ_RETRY_DELAY_US,
 				0, req);
-	if (ret) {
+	kfree(req);
+
+	if (ret)
 		dev_err(psp_i2c_dev, "Timed out waiting for PSP to %s I2C bus\n",
 			(i2c_req_type == PSP_I2C_REQ_ACQUIRE) ?
 			"release" : "acquire");
-		goto cleanup;
-	}
 
-	ret = status;
+	return ret ? ret : status;
+}
+
+static int psp_send_i2c_req(enum psp_i2c_req_type i2c_req_type)
+{
+	const char *hid = acpi_device_hid(ACPI_COMPANION(psp_i2c_dev));
+	unsigned long start = jiffies;
+	int ret;
+
+	/* Use doorbell for Skyrim and mailbox for Cezanne */
+	if (!strcmp(hid, "AMDI0020"))
+		ret = psp_ring_platform_doorbell(i2c_req_type);
+	else
+		ret = psp_send_i2c_req_amdi0019(i2c_req_type);
+
 	if (ret) {
 		dev_err(psp_i2c_dev, "PSP communication error\n");
 		goto cleanup;
@@ -115,7 +125,6 @@ static int psp_send_i2c_req(enum psp_i2c_req_type i2c_req_type)
 		psp_i2c_mbox_fail = true;
 	}
 
-	kfree(req);
 	return ret;
 }
 
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 89ad88c54754..5ca71bda9ac2 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -51,6 +51,7 @@ static const struct acpi_device_id dw_i2c_acpi_match[] = {
 	{ "AMD0010", ACCESS_INTR_MASK },
 	{ "AMDI0010", ACCESS_INTR_MASK },
 	{ "AMDI0019", ACCESS_INTR_MASK | ARBITRATION_SEMAPHORE },
+	{ "AMDI0020", ACCESS_INTR_MASK | ARBITRATION_SEMAPHORE },
 	{ "AMDI0510", 0 },
 	{ "APMC0D0F", 0 },
 	{ "HISI02A1", 0 },
-- 
2.34.1