hwmon: (k10temp) Enable AMD3255 Proc to show negative temperature

commit e146503ac68418859fb063a3a0cd9ec93bc52238 upstream.

Industrial processor i3255 supports temperatures -40 deg celcius
to 105 deg Celcius. The current implementation of k10temp_read_temp
rounds off any negative temperatures to '0'. To fix this,
the following changes have been made.

A flag 'disp_negative' is added to struct k10temp_data to support
AMD i3255 processors. Flag 'disp_negative' is set if 3255 processor
is found during k10temp_probe.  Flag 'disp_negative' is used to
determine whether to round off negative temperatures to '0' in
k10temp_read_temp.

Signed-off-by: Baskaran Kannan <Baski.Kannan@amd.com>
Link: https://lore.kernel.org/r/20230727162159.1056136-1-Baski.Kannan@amd.com
Fixes: aef17ca12719 ("hwmon: (k10temp) Only apply temperature offset if result is positive")
Cc: stable@vger.kernel.org
[groeck: Fixed multi-line comment]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwmon/k10temp.c b/drivers/hwmon/k10temp.c
index e7ba05c50e611059bb4d851e891995e854f26a0b..f3cff6c9f7457e2b9586df1386fea373b74b4c8e 100644 (file)
--- a/drivers/hwmon/k10temp.c
+++ b/drivers/hwmon/k10temp.c
@@ -97,6 +97,13 @@ static DEFINE_MUTEX(nb_smu_ind_mutex);
 #define F19H_M01H_CFACTOR_ICORE                        1000000 /* 1A / LSB     */
 #define F19H_M01H_CFACTOR_ISOC                 310000  /* 0.31A / LSB  */
 
+/*
+ * AMD's Industrial processor 3255 supports temperature from -40 deg to 105 deg Celsius.
+ * Use the model name to identify 3255 CPUs and set a flag to display negative temperature.
+ * Do not round off to zero for negative Tctl or Tdie values if the flag is set
+ */
+#define AMD_I3255_STR                          "3255"
+
 struct k10temp_data {
        struct pci_dev *pdev;
        void (*read_htcreg)(struct pci_dev *pdev, u32 *regval);
@@ -106,6 +113,7 @@ struct k10temp_data {
        u32 show_temp;
        bool is_zen;
        u32 ccd_offset;
+       bool disp_negative;
 };
 
 #define TCTL_BIT       0
@@ -220,12 +228,12 @@ static int k10temp_read_temp(struct device *dev, u32 attr, int channel,
                switch (channel) {
                case 0:         /* Tctl */
                        *val = get_raw_temp(data);
-                       if (*val < 0)
+                       if (*val < 0 && !data->disp_negative)
                                *val = 0;
                        break;
                case 1:         /* Tdie */
                        *val = get_raw_temp(data) - data->temp_offset;
-                       if (*val < 0)
+                       if (*val < 0 && !data->disp_negative)
                                *val = 0;
                        break;
                case 2 ... 9:           /* Tccd{1-8} */
@@ -417,6 +425,11 @@ static int k10temp_probe(struct pci_dev *pdev, const struct pci_device_id *id)
        data->pdev = pdev;
        data->show_temp |= BIT(TCTL_BIT);       /* Always show Tctl */
 
+       if (boot_cpu_data.x86 == 0x17 &&
+           strstr(boot_cpu_data.x86_model_id, AMD_I3255_STR)) {
+               data->disp_negative = true;
+       }
+
        if (boot_cpu_data.x86 == 0x15 &&
            ((boot_cpu_data.x86_model & 0xf0) == 0x60 ||
             (boot_cpu_data.x86_model & 0xf0) == 0x70)) {