ACPI: thinkpad-acpi: clean-up fan subdriver quirk

Better document the Unitialized HFSP quirk, and modularize it a bit.
This makes the code flow easier to read and reduces LOC.

Apply the Unitialized HFSP closer to the source (i.e. inside the
get_fan_status()), this fixes a harmless buglet where at driver init
with the quirk active, the user could set the hwmon pwm1 attribute and
switch out of pwm1_mode=2 to pwm1_mode=0 without changing pwm1_mode
directly.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Tino Keitel <tino.keitel@tikei.de>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 58 insertions, 51 deletions

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index d7d41ae2f299..213219d938e8 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -5897,6 +5897,60 @@ TPACPI_HANDLE(sfan, ec, "SFAN",	/* 570 */
            );                   /* all others */
 
 /*
+ * Unitialized HFSP quirk: ACPI DSDT and EC fail to initialize the
+ * HFSP register at boot, so it contains 0x07 but the Thinkpad could
+ * be in auto mode (0x80).
+ *
+ * This is corrected by any write to HFSP either by the driver, or
+ * by the firmware.
+ *
+ * We assume 0x07 really means auto mode while this quirk is active,
+ * as this is far more likely than the ThinkPad being in level 7,
+ * which is only used by the firmware during thermal emergencies.
+ */
+
+static void fan_quirk1_detect(void)
+{
+        /* In some ThinkPads, neither the EC nor the ACPI
+         * DSDT initialize the HFSP register, and it ends up
+         * being initially set to 0x07 when it *could* be
+         * either 0x07 or 0x80.
+         *
+         * Enable for TP-1Y (T43), TP-78 (R51e),
+         * TP-76 (R52), TP-70 (T43, R52), which are known
+         * to be buggy. */
+        if (fan_control_initial_status == 0x07) {
+                switch (thinkpad_id.ec_model) {
+                case 0x5931: /* TP-1Y */
+                case 0x3837: /* TP-78 */
+                case 0x3637: /* TP-76 */
+                case 0x3037: /* TP-70 */
+                        printk(TPACPI_NOTICE
+                               "fan_init: initial fan status is unknown, "
+                               "assuming it is in auto mode\n");
+                        tp_features.fan_ctrl_status_undef = 1;
+                        ;;
+                }
+        }
+}
+
+static void fan_quirk1_handle(u8 *fan_status)
+{
+        if (unlikely(tp_features.fan_ctrl_status_undef)) {
+                if (*fan_status != fan_control_initial_status) {
+                        /* something changed the HFSP regisnter since
+                         * driver init time, so it is not undefined
+                         * anymore */
+                        tp_features.fan_ctrl_status_undef = 0;
+                } else {
+                        /* Return most likely status. In fact, it
+                         * might be the only possible status */
+                        *fan_status = TP_EC_FAN_AUTO;
+                }
+        }
+}
+
+/*
  * Call with fan_mutex held
  */
 static void fan_update_desired_level(u8 status)
@@ -5934,8 +5988,10 @@ static int fan_get_status(u8 *status)
                 if (unlikely(!acpi_ec_read(fan_status_offset, &s)))
                         return -EIO;
 
-                if (likely(status))
+                if (likely(status)) {
                         *status = s;
+                        fan_quirk1_handle(status);
+                }
 
                 break;
 
@@ -6245,16 +6301,6 @@ static ssize_t fan_pwm1_enable_show(struct device *dev,
         if (res)
                 return res;
 
-        if (unlikely(tp_features.fan_ctrl_status_undef)) {
-                if (status != fan_control_initial_status) {
-                        tp_features.fan_ctrl_status_undef = 0;
-                } else {
-                        /* Return most likely status. In fact, it
-                         * might be the only possible status */
-                        status = TP_EC_FAN_AUTO;
-                }
-        }
-
         if (status & TP_EC_FAN_FULLSPEED) {
                 mode = 0;
         } else if (status & TP_EC_FAN_AUTO) {
@@ -6319,14 +6365,6 @@ static ssize_t fan_pwm1_show(struct device *dev,
         if (res)
                 return res;
 
-        if (unlikely(tp_features.fan_ctrl_status_undef)) {
-                if (status != fan_control_initial_status) {
-                        tp_features.fan_ctrl_status_undef = 0;
-                } else {
-                        status = TP_EC_FAN_AUTO;
-                }
-        }
-
         if ((status &
              (TP_EC_FAN_AUTO | TP_EC_FAN_FULLSPEED)) != 0)
                 status = fan_control_desired_level;
@@ -6458,29 +6496,7 @@ static int __init fan_init(struct ibm_init_struct *iibm)
                 if (likely(acpi_ec_read(fan_status_offset,
                                         &fan_control_initial_status))) {
                         fan_status_access_mode = TPACPI_FAN_RD_TPEC;
-
-                        /* In some ThinkPads, neither the EC nor the ACPI
-                         * DSDT initialize the fan status, and it ends up
-                         * being set to 0x07 when it *could* be either
-                         * 0x07 or 0x80.
-                         *
-                         * Enable for TP-1Y (T43), TP-78 (R51e),
-                         * TP-76 (R52), TP-70 (T43, R52), which are known
-                         * to be buggy. */
-                        if (fan_control_initial_status == 0x07) {
-                                switch (thinkpad_id.ec_model) {
-                                case 0x5931: /* TP-1Y */
-                                case 0x3837: /* TP-78 */
-                                case 0x3637: /* TP-76 */
-                                case 0x3037: /* TP-70 */
-                                        printk(TPACPI_NOTICE
-                                               "fan_init: initial fan status "
-                                               "is unknown, assuming it is "
-                                               "in auto mode\n");
-                                        tp_features.fan_ctrl_status_undef = 1;
-                                        ;;
-                                }
-                        }
+                        fan_quirk1_detect();
                 } else {
                         printk(TPACPI_ERR
                                "ThinkPad ACPI EC access misbehaving, "
@@ -6669,15 +6685,6 @@ static int fan_read(char *p)
                 if (rc < 0)
                         return rc;
 
-                if (unlikely(tp_features.fan_ctrl_status_undef)) {
-                        if (status != fan_control_initial_status)
-                                tp_features.fan_ctrl_status_undef = 0;
-                        else
-                                /* Return most likely status. In fact, it
-                                 * might be the only possible status */
-                                status = TP_EC_FAN_AUTO;
-                }
-
                 len += sprintf(p + len, "status:\t\t%s\n",
                                (status != 0) ? "enabled" : "disabled");