3005-applesmc-basic-mmio-interface-implementation.patch

From 9b452e07d79c0f702f7d22ccc5a12b672d290627 Mon Sep 17 00:00:00 2001
From: Paul Pawlowski <paul@mrarm.io>
Date: Sun, 17 Nov 2019 23:12:16 +0100
Subject: [PATCH 5/6] applesmc: basic mmio interface implementation

This change introduces basic a MMIO-based
interface implementation required to communicate
with the SMC on T2 Macs. The MMIO interface is
enabled only when it's supported on the running
system.

The MMIO interface replaces legacy port-based SMC
key reads, writes and metadata requests (getting
key by index and getting key info).
---
 drivers/hwmon/applesmc.c | 221 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 215 insertions(+), 6 deletions(-)

diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index eda11a6bb327..0cb095ef41a1 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -41,6 +41,18 @@
 
 #define APPLESMC_NR_PORTS	32 /* 0x300-0x31f */
 
+#define APPLESMC_IOMEM_KEY_DATA		0
+#define APPLESMC_IOMEM_KEY_STATUS	0x4005
+#define APPLESMC_IOMEM_KEY_NAME		0x78
+#define APPLESMC_IOMEM_KEY_DATA_LEN	0x7D
+#define APPLESMC_IOMEM_KEY_SMC_ID	0x7E
+#define APPLESMC_IOMEM_KEY_CMD		0x7F
+#define APPLESMC_IOMEM_MIN_SIZE		0x4006
+
+#define APPLESMC_IOMEM_KEY_TYPE_CODE		0
+#define APPLESMC_IOMEM_KEY_TYPE_DATA_LEN	5
+#define APPLESMC_IOMEM_KEY_TYPE_FLAGS		6
+
 #define APPLESMC_MAX_DATA_LENGTH 32
 
 /* wait up to 128 ms for a status change. */
@@ -134,10 +146,13 @@ struct applesmc_registers {
 
 struct applesmc_device {
 	struct acpi_device *dev;
+	struct device *ldev;
 	struct applesmc_registers reg;
 
-	bool port_base_set;
+	bool port_base_set, iomem_base_set;
 	u16 port_base;
+	u8 *__iomem iomem_base;
+	u32 iomem_base_addr, iomem_base_size;
 
 	s16 rest_x;
 	s16 rest_y;
@@ -305,16 +320,141 @@ static int port_get_smc_key_info(struct applesmc_device *smc,
 	return 0;
 }
 
+
+/*
+ * MMIO based communication.
+ */
+
+static void iomem_clear_status(struct applesmc_device *smc)
+{
+	if (ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_STATUS)) {
+		iowrite8(0, smc->iomem_base + APPLESMC_IOMEM_KEY_STATUS);
+	}
+}
+
+static int iomem_wait_read(struct applesmc_device *smc)
+{
+	u8 status;
+	int us;
+	for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
+		udelay(us);
+		status = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_STATUS);
+		if (status & 0x20)
+			return 0;
+		udelay(APPLESMC_RETRY_WAIT);
+	}
+	dev_warn(smc->ldev, "iomem_wait_read() timeout\n");
+	return -EIO;
+}
+
+static int iomem_read_smc(struct applesmc_device *smc, u8 cmd, const char *key,
+	u8 *buffer, u8 len)
+{
+	u8 err, remote_len;
+	u32 key_int = *((u32 *) key);
+	iomem_clear_status(smc);
+	iowrite32(key_int, smc->iomem_base + APPLESMC_IOMEM_KEY_NAME);
+	iowrite32(0, smc->iomem_base + APPLESMC_IOMEM_KEY_SMC_ID);
+	iowrite32(cmd, smc->iomem_base + APPLESMC_IOMEM_KEY_CMD);
+	if (iomem_wait_read(smc)) {
+		return -EIO;
+	}
+	err = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_CMD);
+	if (err != 0) {
+		dev_warn(smc->ldev, "read_smc_mmio(%x %8x/%.4s) failed: %u\n",
+				cmd, key_int, key, err);
+		return -EIO;
+	}
+	if (cmd == APPLESMC_READ_CMD) {
+		remote_len = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_DATA_LEN);
+		if (remote_len != len) {
+			dev_warn(smc->ldev, "read_smc_mmio(%x %8x/%.4s) failed: "
+					"buffer length mismatch (remote = %u, requested = %u)\n",
+					 cmd, key_int, key, remote_len, len);
+			return -EINVAL;
+		}
+	} else {
+		remote_len = len;
+	}
+	memcpy_fromio(buffer, smc->iomem_base + APPLESMC_IOMEM_KEY_DATA,
+			remote_len);
+	dev_dbg(smc->ldev, "read_smc_mmio(%x %8x/%.4s): buflen=%u reslen=%u\n",
+			cmd, key_int, key, len, remote_len);
+	print_hex_dump_bytes("read_smc_mmio(): ", DUMP_PREFIX_NONE, buffer, remote_len);
+	return 0;
+}
+
+static int iomem_get_smc_key_type(struct applesmc_device *smc, const char *key,
+	struct applesmc_entry *e)
+{
+	u8 err;
+	u8 cmd = APPLESMC_GET_KEY_TYPE_CMD;
+	u32 key_int = *((u32 *) key);
+	iomem_clear_status(smc);
+	iowrite32(key_int, smc->iomem_base + APPLESMC_IOMEM_KEY_NAME);
+	iowrite32(0, smc->iomem_base + APPLESMC_IOMEM_KEY_SMC_ID);
+	iowrite32(cmd, smc->iomem_base + APPLESMC_IOMEM_KEY_CMD);
+	if (iomem_wait_read(smc)) {
+		return -EIO;
+	}
+	err = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_CMD);
+	if (err != 0) {
+		dev_warn(smc->ldev, "get_smc_key_type_mmio(%.4s) failed: %u\n", key, err);
+		return -EIO;
+	}
+	e->len = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_TYPE_DATA_LEN);
+	*((uint32_t *) e->type) = ioread32(
+			smc->iomem_base + APPLESMC_IOMEM_KEY_TYPE_CODE);
+	e->flags = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_TYPE_FLAGS);
+	dev_dbg(smc->ldev, "get_smc_key_type_mmio(%.4s): "
+			"len=%u type=%.4s flags=%x\n", key, e->len, e->type, e->flags);
+	return 0;
+}
+
+static int iomem_write_smc(struct applesmc_device *smc, u8 cmd, const char *key, const u8 *buffer, u8 len)
+{
+	u8 err;
+	u32 key_int = *((u32 *) key);
+	iomem_clear_status(smc);
+	iowrite32(key_int, smc->iomem_base + APPLESMC_IOMEM_KEY_NAME);
+	memcpy_toio(smc->iomem_base + APPLESMC_IOMEM_KEY_DATA, buffer, len);
+	iowrite32(len, smc->iomem_base + APPLESMC_IOMEM_KEY_DATA_LEN);
+	iowrite32(0, smc->iomem_base + APPLESMC_IOMEM_KEY_SMC_ID);
+	iowrite32(cmd , smc->iomem_base + APPLESMC_IOMEM_KEY_CMD);
+	if (iomem_wait_read(smc)) {
+		return -EIO;
+	}
+	err = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_CMD);
+	if (err != 0) {
+		dev_warn(smc->ldev, "write_smc_mmio(%x %.4s) failed: %u\n", cmd, key, err);
+		print_hex_dump_bytes("write_smc_mmio(): ", DUMP_PREFIX_NONE, buffer, len);
+		return -EIO;
+	}
+	dev_dbg(smc->ldev, "write_smc_mmio(%x %.4s): buflen=%u\n",
+			cmd, key, len);
+	print_hex_dump_bytes("write_smc_mmio(): ", DUMP_PREFIX_NONE, buffer, len);
+	return 0;
+}
+
+
 static int read_smc(struct applesmc_device *smc, const char *key,
 	u8 *buffer, u8 len)
 {
-	return port_read_smc(smc, APPLESMC_READ_CMD, key, buffer, len);
+	if (smc->iomem_base_set) {
+		return iomem_read_smc(smc, APPLESMC_READ_CMD, key, buffer, len);
+	} else {
+		return port_read_smc(smc, APPLESMC_READ_CMD, key, buffer, len);
+	}
 }
 
 static int write_smc(struct applesmc_device *smc, const char *key,
 	const u8 *buffer, u8 len)
 {
-	return port_write_smc(smc, APPLESMC_WRITE_CMD, key, buffer, len);
+	if (smc->iomem_base_set) {
+		return iomem_write_smc(smc, APPLESMC_WRITE_CMD, key, buffer, len);
+	} else {
+		return port_write_smc(smc, APPLESMC_WRITE_CMD, key, buffer, len);
+	}
 }
 
 static int get_smc_key_by_index(struct applesmc_device *smc,
@@ -322,14 +462,23 @@ static int get_smc_key_by_index(struct applesmc_device *smc,
 {
 	__be32 be;
 	be = cpu_to_be32(index);
-	return port_read_smc(smc, APPLESMC_GET_KEY_BY_INDEX_CMD,
-			(const char *) &be, (u8 *) key, 4);
+	if (smc->iomem_base_set) {
+		return iomem_read_smc(smc, APPLESMC_GET_KEY_BY_INDEX_CMD,
+							  (const char *) &be, (u8 *) key, 4);
+	} else {
+		return port_read_smc(smc, APPLESMC_GET_KEY_BY_INDEX_CMD,
+							 (const char *) &be, (u8 *) key, 4);
+	}
 }
 
 static int get_smc_key_info(struct applesmc_device *smc, const char *key,
 	struct applesmc_entry *info)
 {
-	return port_get_smc_key_info(smc, key, info);
+	if (smc->iomem_base_set) {
+		return iomem_get_smc_key_type(smc, key, info);
+	} else {
+		return port_get_smc_key_info(smc, key, info);
+	}
 }
 
 static int read_register_count(struct applesmc_device *smc,
@@ -703,6 +852,7 @@ static int applesmc_add(struct acpi_device *dev)
 	if (!smc)
 		return -ENOMEM;
 	smc->dev = dev;
+	smc->ldev = &dev->dev;
 	mutex_init(&smc->reg.mutex);
 
 	dev_set_drvdata(&dev->dev, smc);
@@ -764,6 +914,20 @@ static acpi_status applesmc_walk_resources(struct acpi_resource *res,
 			}
 			return AE_OK;
 
+		case ACPI_RESOURCE_TYPE_FIXED_MEMORY32:
+			if (!smc->iomem_base_set) {
+				if (res->data.fixed_memory32.address_length <
+						APPLESMC_IOMEM_MIN_SIZE) {
+					dev_warn(smc->ldev, "found iomem but it's too small: %u\n",
+							 res->data.fixed_memory32.address_length);
+					return AE_OK;
+				}
+				smc->iomem_base_addr = res->data.fixed_memory32.address;
+				smc->iomem_base_size = res->data.fixed_memory32.address_length;
+				smc->iomem_base_set = true;
+			}
+			return AE_OK;
+
 		case ACPI_RESOURCE_TYPE_END_TAG:
 			if (smc->port_base_set)
 				return AE_OK;
@@ -775,6 +939,8 @@ static acpi_status applesmc_walk_resources(struct acpi_resource *res,
 	}
 }
 
+static int applesmc_try_enable_iomem(struct applesmc_device *smc);
+
 static int applesmc_init_resources(struct applesmc_device *smc)
 {
 	int ret;
@@ -787,11 +953,54 @@ static int applesmc_init_resources(struct applesmc_device *smc)
 	if (!request_region(smc->port_base, APPLESMC_NR_PORTS, "applesmc"))
 		return -ENXIO;
 
+	if (smc->iomem_base_set) {
+		if (applesmc_try_enable_iomem(smc))
+			smc->iomem_base_set = false;
+	}
+
+	return 0;
+}
+
+static int applesmc_try_enable_iomem(struct applesmc_device *smc)
+{
+	u8 test_val, ldkn_version;
+
+	dev_dbg(smc->ldev, "Trying to enable iomem based communication\n");
+	smc->iomem_base = ioremap(smc->iomem_base_addr, smc->iomem_base_size);
+	if (!smc->iomem_base)
+		goto out;
+
+	/* Apple's driver does this check for some reason */
+	test_val = ioread8(smc->iomem_base + APPLESMC_IOMEM_KEY_STATUS);
+	if (test_val == 0xff) {
+		dev_warn(smc->ldev, "iomem enable failed: "
+				"initial status is 0xff (is %x)\n", test_val);
+		goto out_iomem;
+	}
+
+	if (read_smc(smc, "LDKN", &ldkn_version, 1)) {
+		dev_warn(smc->ldev, "iomem enable failed: ldkn read failed\n");
+		goto out_iomem;
+	}
+
+	if (ldkn_version < 2) {
+		dev_warn(smc->ldev, "iomem enable failed: "
+				"ldkn version %u is less than minimum (2)\n", ldkn_version);
+		goto out_iomem;
+	}
+
 	return 0;
+
+out_iomem:
+	iounmap(smc->iomem_base);
+out:
+	return -ENXIO;
 }
 
 static void applesmc_free_resources(struct applesmc_device *smc)
 {
+	if (smc->iomem_base_set)
+		iounmap(smc->iomem_base);
 	release_region(smc->port_base, APPLESMC_NR_PORTS);
 }
 
-- 
2.25.0