x86/amd_nb: Add SMN and Indirect Data Fabric access for AMD Fam17h

Some devices on Fam17h can only be accessed through the System Management
Network (SMN). The SMN is accessed by a pair of index/data registers in PCI
config space. Add a pair of functions to read from and write to the SMN.

The Data Fabric on Fam17h allows multiple devices to use the same register
space. The registers of a specific device are accessed indirectly using the
device's DF InstanceId. Currently, we only need to read from these devices,
so only define a read function for now.
Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/1478812257-5424-5-git-send-email-Yazen.Ghannam@amd.com
[ Boris: make __amd_smn_rw() even more compact. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/amd_nb.h

@@ -21,6 +21,10 @@ extern int amd_numa_init(void);
 extern int amd_get_subcaches(int);
 extern int amd_set_subcaches(int, unsigned long);
 
+extern int amd_smn_read(u16 node, u32 address, u32 *value);
+extern int amd_smn_write(u16 node, u32 address, u32 value);
+extern int amd_df_indirect_read(u16 node, u8 func, u16 reg, u8 instance_id, u32 *lo);
+
 struct amd_l3_cache {
 	unsigned indices;
 	u8	 subcaches[4];
@@ -55,6 +59,7 @@ struct threshold_bank {
 };
 
 struct amd_northbridge {
+	struct pci_dev *root;
 	struct pci_dev *misc;
 	struct pci_dev *link;
 	struct amd_l3_cache l3_cache;

arch/x86/kernel/amd_nb.c

@@ -13,11 +13,20 @@
 #include <linux/spinlock.h>
 #include <asm/amd_nb.h>
 
+#define PCI_DEVICE_ID_AMD_17H_ROOT	0x1450
 #define PCI_DEVICE_ID_AMD_17H_DF_F3	0x1463
 #define PCI_DEVICE_ID_AMD_17H_DF_F4	0x1464
 
+/* Protect the PCI config register pairs used for SMN and DF indirect access. */
+static DEFINE_MUTEX(smn_mutex);
+
 static u32 *flush_words;
 
+static const struct pci_device_id amd_root_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_ROOT) },
+	{}
+};
+
 const struct pci_device_id amd_nb_misc_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB_MISC) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_10H_NB_MISC) },
@@ -80,11 +89,104 @@ static struct pci_dev *next_northbridge(struct pci_dev *dev,
 	return dev;
 }
 
+static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
+{
+	struct pci_dev *root;
+	int err = -ENODEV;
+
+	if (node >= amd_northbridges.num)
+		goto out;
+
+	root = node_to_amd_nb(node)->root;
+	if (!root)
+		goto out;
+
+	mutex_lock(&smn_mutex);
+
+	err = pci_write_config_dword(root, 0x60, address);
+	if (err) {
+		pr_warn("Error programming SMN address 0x%x.\n", address);
+		goto out_unlock;
+	}
+
+	err = (write ? pci_write_config_dword(root, 0x64, *value)
+		     : pci_read_config_dword(root, 0x64, value));
+	if (err)
+		pr_warn("Error %s SMN address 0x%x.\n",
+			(write ? "writing to" : "reading from"), address);
+
+out_unlock:
+	mutex_unlock(&smn_mutex);
+
+out:
+	return err;
+}
+
+int amd_smn_read(u16 node, u32 address, u32 *value)
+{
+	return __amd_smn_rw(node, address, value, false);
+}
+EXPORT_SYMBOL_GPL(amd_smn_read);
+
+int amd_smn_write(u16 node, u32 address, u32 value)
+{
+	return __amd_smn_rw(node, address, &value, true);
+}
+EXPORT_SYMBOL_GPL(amd_smn_write);
+
+/*
+ * Data Fabric Indirect Access uses FICAA/FICAD.
+ *
+ * Fabric Indirect Configuration Access Address (FICAA): Constructed based
+ * on the device's Instance Id and the PCI function and register offset of
+ * the desired register.
+ *
+ * Fabric Indirect Configuration Access Data (FICAD): There are FICAD LO
+ * and FICAD HI registers but so far we only need the LO register.
+ */
+int amd_df_indirect_read(u16 node, u8 func, u16 reg, u8 instance_id, u32 *lo)
+{
+	struct pci_dev *F4;
+	u32 ficaa;
+	int err = -ENODEV;
+
+	if (node >= amd_northbridges.num)
+		goto out;
+
+	F4 = node_to_amd_nb(node)->link;
+	if (!F4)
+		goto out;
+
+	ficaa  = 1;
+	ficaa |= reg & 0x3FC;
+	ficaa |= (func & 0x7) << 11;
+	ficaa |= instance_id << 16;
+
+	mutex_lock(&smn_mutex);
+
+	err = pci_write_config_dword(F4, 0x5C, ficaa);
+	if (err) {
+		pr_warn("Error writing DF Indirect FICAA, FICAA=0x%x\n", ficaa);
+		goto out_unlock;
+	}
+
+	err = pci_read_config_dword(F4, 0x98, lo);
+	if (err)
+		pr_warn("Error reading DF Indirect FICAD LO, FICAA=0x%x.\n", ficaa);
+
+out_unlock:
+	mutex_unlock(&smn_mutex);
+
+out:
+	return err;
+}
+EXPORT_SYMBOL_GPL(amd_df_indirect_read);
+
 int amd_cache_northbridges(void)
 {
 	u16 i = 0;
 	struct amd_northbridge *nb;
-	struct pci_dev *misc, *link;
+	struct pci_dev *root, *misc, *link;
 
 	if (amd_northbridges.num)
 		return 0;
@@ -103,8 +205,10 @@ int amd_cache_northbridges(void)
 	amd_northbridges.nb = nb;
 	amd_northbridges.num = i;
 
-	link = misc = NULL;
+	link = misc = root = NULL;
 	for (i = 0; i != amd_northbridges.num; i++) {
+		node_to_amd_nb(i)->root = root =
+			next_northbridge(root, amd_root_ids);
 		node_to_amd_nb(i)->misc = misc =
 			next_northbridge(misc, amd_nb_misc_ids);
 		node_to_amd_nb(i)->link = link =