platform/x86: amd-pmc: Move FCH init to first use

FCH address is accessed only when looking at s0ix stats.

As this is unnecessary for initialization, move it ito the first
time stats are accessed from sysfs.  This descrease startup time
by about 200us.
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20220411143820.13971-2-mario.limonciello@amd.comSigned-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/amd-pmc.c

@@ -387,6 +387,17 @@ static int s0ix_stats_show(struct seq_file *s, void *unused)
 	struct amd_pmc_dev *dev = s->private;
 	u64 entry_time, exit_time, residency;
 
+	/* Use FCH registers to get the S0ix stats */
+	if (!dev->fch_virt_addr) {
+		u32 base_addr_lo = FCH_BASE_PHY_ADDR_LOW;
+		u32 base_addr_hi = FCH_BASE_PHY_ADDR_HIGH;
+		u64 fch_phys_addr = ((u64)base_addr_hi << 32 | base_addr_lo);
+
+		dev->fch_virt_addr = devm_ioremap(dev->dev, fch_phys_addr, FCH_SSC_MAPPING_SIZE);
+		if (!dev->fch_virt_addr)
+			return -ENOMEM;
+	}
+
 	entry_time = ioread32(dev->fch_virt_addr + FCH_S0I3_ENTRY_TIME_H_OFFSET);
 	entry_time = entry_time << 32 | ioread32(dev->fch_virt_addr + FCH_S0I3_ENTRY_TIME_L_OFFSET);
 
@@ -804,7 +815,7 @@ static int amd_pmc_probe(struct platform_device *pdev)
 	struct amd_pmc_dev *dev = &pmc;
 	struct pci_dev *rdev;
 	u32 base_addr_lo, base_addr_hi;
-	u64 base_addr, fch_phys_addr;
+	u64 base_addr;
 	int err;
 	u32 val;
 
@@ -858,16 +869,6 @@ static int amd_pmc_probe(struct platform_device *pdev)
 
 	mutex_init(&dev->lock);
 
-	/* Use FCH registers to get the S0ix stats */
-	base_addr_lo = FCH_BASE_PHY_ADDR_LOW;
-	base_addr_hi = FCH_BASE_PHY_ADDR_HIGH;
-	fch_phys_addr = ((u64)base_addr_hi << 32 | base_addr_lo);
-	dev->fch_virt_addr = devm_ioremap(dev->dev, fch_phys_addr, FCH_SSC_MAPPING_SIZE);
-	if (!dev->fch_virt_addr) {
-		err = -ENOMEM;
-		goto err_pci_dev_put;
-	}
-
 	if (enable_stb && dev->cpu_id == AMD_CPU_ID_YC) {
 		err = amd_pmc_s2d_init(dev);
 		if (err)