platform/chrome: cros_ec_lpc: introduce a priv struct for the lpc device

lpc_driver_data stores the MMIO port base for EC mapped memory.
cros_ec_lpc_readmem uses this port base instead of hardcoding
EC_LPC_ADDR_MEMMAP.

Signed-off-by: Dustin L. Howett <dustin@howett.net>
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Tested-by: Thomas Weißschuh <linux@weissschuh.net>
Tested-by: Mario Limonciello <superm1@gmail.com>
Link: https://lore.kernel.org/r/20240403004713.130365-2-dustin@howett.net
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

Author: DHowett

drivers/platform/chrome/cros_ec_lpc.c

@@ -34,6 +34,14 @@
 /* True if ACPI device is present */
 static bool cros_ec_lpc_acpi_device_found;
 
+/**
+ * struct cros_ec_lpc - LPC device-specific data
+ * @mmio_memory_base: The first I/O port addressing EC mapped memory.
+ */
+struct cros_ec_lpc {
+	u16 mmio_memory_base;
+};
+
 /**
  * struct lpc_driver_ops - LPC driver operations
  * @read: Copy length bytes from EC address offset into buffer dest. Returns
@@ -290,6 +298,7 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 			       unsigned int bytes, void *dest)
 {
+	struct cros_ec_lpc *ec_lpc = ec->priv;
 	int i = offset;
 	char *s = dest;
 	int cnt = 0;
@@ -299,13 +308,13 @@ static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 
 	/* fixed length */
 	if (bytes) {
-		cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
+		cros_ec_lpc_ops.read(ec_lpc->mmio_memory_base + offset, bytes, s);
 		return bytes;
 	}
 
 	/* string */
 	for (; i < EC_MEMMAP_SIZE; i++, s++) {
-		cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + i, 1, s);
+		cros_ec_lpc_ops.read(ec_lpc->mmio_memory_base + i, 1, s);
 		cnt++;
 		if (!*s)
 			break;
@@ -353,9 +362,16 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 	struct acpi_device *adev;
 	acpi_status status;
 	struct cros_ec_device *ec_dev;
+	struct cros_ec_lpc *ec_lpc;
 	u8 buf[2] = {};
 	int irq, ret;
 
+	ec_lpc = devm_kzalloc(dev, sizeof(*ec_lpc), GFP_KERNEL);
+	if (!ec_lpc)
+		return -ENOMEM;
+
+	ec_lpc->mmio_memory_base = EC_LPC_ADDR_MEMMAP;
+
 	/*
 	 * The Framework Laptop (and possibly other non-ChromeOS devices)
 	 * only exposes the eight I/O ports that are required for the Microchip EC.
@@ -380,7 +396,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 	cros_ec_lpc_ops.write = cros_ec_lpc_mec_write_bytes;
 	cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
 	if (buf[0] != 'E' || buf[1] != 'C') {
-		if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
+		if (!devm_request_region(dev, ec_lpc->mmio_memory_base, EC_MEMMAP_SIZE,
 					 dev_name(dev))) {
 			dev_err(dev, "couldn't reserve memmap region\n");
 			return -EBUSY;
@@ -389,7 +405,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 		/* Re-assign read/write operations for the non MEC variant */
 		cros_ec_lpc_ops.read = cros_ec_lpc_read_bytes;
 		cros_ec_lpc_ops.write = cros_ec_lpc_write_bytes;
-		cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2,
+		cros_ec_lpc_ops.read(ec_lpc->mmio_memory_base + EC_MEMMAP_ID, 2,
 				     buf);
 		if (buf[0] != 'E' || buf[1] != 'C') {
 			dev_err(dev, "EC ID not detected\n");
@@ -423,6 +439,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 	ec_dev->din_size = sizeof(struct ec_host_response) +
 			   sizeof(struct ec_response_get_protocol_info);
 	ec_dev->dout_size = sizeof(struct ec_host_request);
+	ec_dev->priv = ec_lpc;
 
 	/*
 	 * Some boards do not have an IRQ allotted for cros_ec_lpc,