[PATCH] cpufreq/amd-pstate: Supply nominal/lowest freq for TRX40-based motherboards

[Giovanni Gherdovich <ggherdovich@suse.cz>]

Some motherboard based on the TRX40 chipset has been reported to ship
firmware lacking lowest and nominal frequency values in the
_CPC ACPI package. That is, it supports CPPC V2 but not CPPC V3.
Firmware updates aren't available.

amd-pstate requires explicit knowledge of nominal frequency, so it
can't load on this hardware. The driver already has a mechanism (the
so-called "quirks") to accommodate for missing nominal freq in ACPI
tables, so here we use it to match against CPU family, model, core
count, and BIOS version.

Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
---
 drivers/cpufreq/amd-pstate.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 8bfd46d60843..532ff16dd076 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -145,6 +145,11 @@ static struct quirk_entry quirk_amd_7k62 = {
 	.lowest_freq = 550,
 };
 
+static struct quirk_entry quirk_amd_ryzen_threadripper_3000_24c = {
+	.nominal_freq = 3800,
+	.lowest_freq = 550,
+};
+
 static inline u8 freq_to_perf(union perf_cached perf, u32 nominal_freq, unsigned int freq_val)
 {
 	u32 perf_val = DIV_ROUND_UP_ULL((u64)freq_val * perf.nominal_perf, nominal_freq);
@@ -174,6 +179,22 @@ static int __init dmi_matched_7k62_bios_bug(const struct dmi_system_id *dmi)
 	return 0;
 }
 
+static int __init dmi_matched_trx40_bios_bug(const struct dmi_system_id *dmi)
+{
+	/**
+	 * Match the Ryzen Threadripper 3000 series, 24-core SKU, sTRX4 socket / TRX40 chipset.
+	 */
+	if (boot_cpu_data.x86 == 0x17 &&
+	    boot_cpu_data.x86_model >= 0x30 && boot_cpu_data.x86_model <= 0x3F &&
+	    topology_num_cores_per_package() == 24) {
+		quirks = dmi->driver_data;
+		pr_info("Overriding nominal and lowest frequencies for %s\n", dmi->ident);
+		return 1;
+	}
+
+	return 0;
+}
+
 static const struct dmi_system_id amd_pstate_quirks_table[] __initconst = {
 	{
 		.callback = dmi_matched_7k62_bios_bug,
@@ -184,6 +205,16 @@ static const struct dmi_system_id amd_pstate_quirks_table[] __initconst = {
 		},
 		.driver_data = &quirk_amd_7k62,
 	},
+	{
+		.callback = dmi_matched_trx40_bios_bug,
+		.ident = "AMD Ryzen Threadripper 3000",
+		.matches = {
+			DMI_MATCH(DMI_BIOS_VENDOR,  "American Megatrends International"),
+			DMI_MATCH(DMI_BIOS_VERSION, "2.80"),
+			DMI_MATCH(DMI_BIOS_DATE,    "05/17/2022"),
+		},
+		.driver_data = &quirk_amd_ryzen_threadripper_3000_24c,
+	},
 	{}
 };
 MODULE_DEVICE_TABLE(dmi, amd_pstate_quirks_table);
-- 
2.43.0