platform/x86: pmc_atom: improve critclk_systems matching for Siemens PCs

Siemens industrial PCs unfortunately can not always be properly
identified the way we used to. An earlier commit introduced code that
allows proper identification without looking at DMI strings that could
differ based on product branding.
Switch over to that proper way and revert commits that used to collect
the machines based on unstable strings.

Fixes: 648e921 ("clk: x86: Stop marking clocks as CLK_IS_CRITICAL")
Fixes: e8796c6 ("platform/x86: pmc_atom: Add Siemens CONNECT ...")
Fixes: f110d25 ("platform/x86: pmc_atom: Add Siemens SIMATIC ...")
Fixes: ad0d315 ("platform/x86: pmc_atom: Add Siemens SIMATIC ...")
Tested-by: Michael Haener <michael.haener@siemens.com>
Signed-off-by: Henning Schild <henning.schild@siemens.com>

drivers/platform/x86/pmc_atom.c

@@ -13,6 +13,7 @@
 #include <linux/io.h>
 #include <linux/platform_data/x86/clk-pmc-atom.h>
 #include <linux/platform_data/x86/pmc_atom.h>
+#include <linux/platform_data/x86/simatic-ipc.h>
 #include <linux/platform_device.h>
 #include <linux/pci.h>
 #include <linux/seq_file.h>
@@ -362,6 +363,23 @@ static void pmc_dbgfs_register(struct pmc_dev *pmc)
 }
 #endif /* CONFIG_DEBUG_FS */
 
+static bool pmc_clk_is_critical = true;
+
+static int siemens_clk_is_critical(const struct dmi_system_id *d)
+{
+	u32 st_id;
+
+	if (dmi_walk(simatic_ipc_find_dmi_entry_helper, &st_id))
+		goto out;
+
+	if (st_id == SIMATIC_IPC_IPC227E || st_id == SIMATIC_IPC_IPC277E)
+		return 1;
+
+out:
+	pmc_clk_is_critical = false;
+	return 1;
+}
+
 /*
  * Some systems need one or more of their pmc_plt_clks to be
  * marked as critical.
@@ -424,24 +442,10 @@ static const struct dmi_system_id critclk_systems[] = {
 		},
 	},
 	{
-		.ident = "SIMATIC IPC227E",
-		.matches = {
-			DMI_MATCH(DMI_SYS_VENDOR, "SIEMENS AG"),
-			DMI_MATCH(DMI_PRODUCT_VERSION, "6ES7647-8B"),
-		},
-	},
-	{
-		.ident = "SIMATIC IPC277E",
-		.matches = {
-			DMI_MATCH(DMI_SYS_VENDOR, "SIEMENS AG"),
-			DMI_MATCH(DMI_PRODUCT_VERSION, "6AV7882-0"),
-		},
-	},
-	{
-		.ident = "CONNECT X300",
+		.callback = siemens_clk_is_critical,
+		.ident = "SIEMENS AG",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "SIEMENS AG"),
-			DMI_MATCH(DMI_PRODUCT_VERSION, "A5E45074588"),
 		},
 	},
 
@@ -453,17 +457,20 @@ static int pmc_setup_clks(struct pci_dev *pdev, void __iomem *pmc_regmap,
 {
 	struct platform_device *clkdev;
 	struct pmc_clk_data *clk_data;
-	const struct dmi_system_id *d = dmi_first_match(critclk_systems);
+	const struct dmi_system_id *d;
 
 	clk_data = kzalloc(sizeof(*clk_data), GFP_KERNEL);
 	if (!clk_data)
 		return -ENOMEM;
 
 	clk_data->base = pmc_regmap; /* offset is added by client */
 	clk_data->clks = pmc_data->clks;
-	if (d) {
-		clk_data->critical = true;
-		pr_info("%s critclks quirk enabled\n", d->ident);
+	if (dmi_check_system(critclk_systems)) {
+		clk_data->critical = pmc_clk_is_critical;
+		if (clk_data->critical) {
+			d = dmi_first_match(critclk_systems);
+			pr_info("%s critclks quirk enabled\n", d->ident);
+		}
 	}
 
 	clkdev = platform_device_register_data(&pdev->dev, "clk-pmc-atom",