platform/x86: panasonic-laptop: Add sysfs attributes for firmware brightness registers

Panasonic laptops (at least from CF-W4 onwards) have dedicated firmware
registers for saving ac/dc and current brightness. They are a bit confusing
so here's some explanations:

AC_MIN_BRIGHT, AC_MAX_BRIGHT, DC_MIN_BRIGHT, DC_MAX_BRIGHT:
Read-only. Values: 0x01 and 0x15 respectively.

AC_CUR_BRIGHT, DC_CUR_BRIGHT:
Read-Write. 0x00-0xFF. Store user-defined AC/DC brightness. However,
they do not represent current brightness so they should be named AC_BRIGHT
and DC_BRIGHT instead.

CUR_BRIGHT (present since CF-W4):
Read-Write. 0x00-0xFF. It sets the current brightness. It won't update
itself if brightness is changed via other means, e.g. acpi_video0.

Another CUR_BRIGHT (added since CF-W5):
Read-Write. 0x01-0x15. Its value always synchronizes with current
brightness. Not implemented in this version.

Currently the backlight API interacts with AC_CUR_BRIGHT (probably because
it's the only bl register available in earlier models?). This patch adds
sysfs attributes for AC_CUR_BRIGHT, DC_CUR_BRIGHT and CUR_BRIGHT.

It also fixes the error of https://lkml.org/lkml/2020/8/19/1264.

PS: I think the backlight API should interact with CUR_BRIGHT instead of
AC_CUR_BRIGHT. But it involves complications like mapping between 0x01-0x15
or 0x00-0x14 (the backlight API) and 0x00-0xFF (CUR_BRIGHT). I'll leave the
discussion for a later version.

Signed-off-by: Kenneth Chan <kenneth.t.chan@gmail.com>
Link: https://lore.kernel.org/r/20200821181433.17653-10-kenneth.t.chan@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index 6355d60..6388c3c 100644 (file)
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -13,6 +13,7 @@
  *
  * ChangeLog:
  *     Aug.18, 2020    Kenneth Chan <kenneth.t.chan@gmail.com>
+ *             -v0.98  add platform devices for firmware brightness registers
  *                     add support for battery charging threshold (eco mode)
  *                     resolve hotkey double trigger
  *                     add write support to mute
@@ -132,6 +133,7 @@
 #include <linux/input/sparse-keymap.h>
 #include <linux/platform_device.h>
 
+
 MODULE_AUTHOR("Hiroshi Miura <miura@da-cha.org>");
 MODULE_AUTHOR("David Bronaugh <dbronaugh@linuxboxen.org>");
 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
@@ -173,6 +175,7 @@ enum SINF_BITS { SINF_NUM_BATTERIES = 0,
                 SINF_MUTE,
                 SINF_RESERVED,
                 SINF_ECO_MODE = 0x0A,
+                SINF_CUR_BRIGHT = 0x0D,
                 SINF_STICKY_KEY = 0x80,
        };
 /* R1 handles SINF_AC_CUR_BRIGHT as SINF_CUR_BRIGHT, doesn't know AC state */
@@ -228,6 +231,9 @@ struct pcc_acpi {
        int                     sticky_key;
        int                     eco_mode;
        int                     mute;
+       int                     ac_brightness;
+       int                     dc_brightness;
+       int                     current_brightness;
        u32                     *sinf;
        struct acpi_device      *device;
        struct input_dev        *input_dev;
@@ -610,6 +616,97 @@ static ssize_t eco_mode_store(struct device *dev, struct device_attribute *attr,
        return count;
 }
 
+static ssize_t ac_brightness_show(struct device *dev, struct device_attribute *attr,
+                                 char *buf)
+{
+       struct acpi_device *acpi = to_acpi_device(dev);
+       struct pcc_acpi *pcc = acpi_driver_data(acpi);
+
+       if (!acpi_pcc_retrieve_biosdata(pcc))
+               return -EIO;
+
+       return snprintf(buf, PAGE_SIZE, "%u\n", pcc->sinf[SINF_AC_CUR_BRIGHT]);
+}
+
+static ssize_t ac_brightness_store(struct device *dev, struct device_attribute *attr,
+                                  const char *buf, size_t count)
+{
+       struct acpi_device *acpi = to_acpi_device(dev);
+       struct pcc_acpi *pcc = acpi_driver_data(acpi);
+       int err, val;
+
+       err = kstrtoint(buf, 0, &val);
+       if (err)
+               return err;
+       if (val >= 0 && val <= 255) {
+               acpi_pcc_write_sset(pcc, SINF_AC_CUR_BRIGHT, val);
+               pcc->ac_brightness = val;
+       }
+
+       return count;
+}
+
+static ssize_t dc_brightness_show(struct device *dev, struct device_attribute *attr,
+                                 char *buf)
+{
+       struct acpi_device *acpi = to_acpi_device(dev);
+       struct pcc_acpi *pcc = acpi_driver_data(acpi);
+
+       if (!acpi_pcc_retrieve_biosdata(pcc))
+               return -EIO;
+
+       return snprintf(buf, PAGE_SIZE, "%u\n", pcc->sinf[SINF_DC_CUR_BRIGHT]);
+}
+
+static ssize_t dc_brightness_store(struct device *dev, struct device_attribute *attr,
+                                  const char *buf, size_t count)
+{
+       struct acpi_device *acpi = to_acpi_device(dev);
+       struct pcc_acpi *pcc = acpi_driver_data(acpi);
+       int err, val;
+
+       err = kstrtoint(buf, 0, &val);
+       if (err)
+               return err;
+       if (val >= 0 && val <= 255) {
+               acpi_pcc_write_sset(pcc, SINF_DC_CUR_BRIGHT, val);
+               pcc->dc_brightness = val;
+       }
+
+       return count;
+}
+
+static ssize_t current_brightness_show(struct device *dev, struct device_attribute *attr,
+                                      char *buf)
+{
+       struct acpi_device *acpi = to_acpi_device(dev);
+       struct pcc_acpi *pcc = acpi_driver_data(acpi);
+
+       if (!acpi_pcc_retrieve_biosdata(pcc))
+               return -EIO;
+
+       return snprintf(buf, PAGE_SIZE, "%u\n", pcc->sinf[SINF_CUR_BRIGHT]);
+}
+
+static ssize_t current_brightness_store(struct device *dev, struct device_attribute *attr,
+                                       const char *buf, size_t count)
+{
+       struct acpi_device *acpi = to_acpi_device(dev);
+       struct pcc_acpi *pcc = acpi_driver_data(acpi);
+       int err, val;
+
+       err = kstrtoint(buf, 0, &val);
+       if (err)
+               return err;
+
+       if (val >= 0 && val <= 255) {
+               err = acpi_pcc_write_sset(pcc, SINF_CUR_BRIGHT, val);
+               pcc->current_brightness = val;
+       }
+
+       return count;
+}
+
 static ssize_t cdpower_show(struct device *dev, struct device_attribute *attr,
                            char *buf)
 {
@@ -633,6 +730,9 @@ static DEVICE_ATTR_RO(lcdtype);
 static DEVICE_ATTR_RW(mute);
 static DEVICE_ATTR_RW(sticky_key);
 static DEVICE_ATTR_RW(eco_mode);
+static DEVICE_ATTR_RW(ac_brightness);
+static DEVICE_ATTR_RW(dc_brightness);
+static DEVICE_ATTR_RW(current_brightness);
 static DEVICE_ATTR_RW(cdpower);
 
 static struct attribute *pcc_sysfs_entries[] = {
@@ -641,6 +741,9 @@ static struct attribute *pcc_sysfs_entries[] = {
        &dev_attr_mute.attr,
        &dev_attr_sticky_key.attr,
        &dev_attr_eco_mode.attr,
+       &dev_attr_ac_brightness.attr,
+       &dev_attr_dc_brightness.attr,
+       &dev_attr_current_brightness.attr,
        &dev_attr_cdpower.attr,
        NULL,
 };
@@ -794,6 +897,9 @@ static int acpi_pcc_hotkey_resume(struct device *dev)
        acpi_pcc_write_sset(pcc, SINF_MUTE, pcc->mute);
        acpi_pcc_write_sset(pcc, SINF_ECO_MODE, pcc->eco_mode);
        acpi_pcc_write_sset(pcc, SINF_STICKY_KEY, pcc->sticky_key);
+       acpi_pcc_write_sset(pcc, SINF_AC_CUR_BRIGHT, pcc->ac_brightness);
+       acpi_pcc_write_sset(pcc, SINF_DC_CUR_BRIGHT, pcc->dc_brightness);
+       acpi_pcc_write_sset(pcc, SINF_CUR_BRIGHT, pcc->current_brightness);
 
        return 0;
 }
@@ -865,6 +971,9 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 
        pcc->eco_mode = pcc->sinf[SINF_ECO_MODE];
        pcc->mute = pcc->sinf[SINF_MUTE];
+       pcc->ac_brightness = pcc->sinf[SINF_AC_CUR_BRIGHT];
+       pcc->dc_brightness = pcc->sinf[SINF_DC_CUR_BRIGHT];
+       result = pcc->current_brightness = pcc->sinf[SINF_CUR_BRIGHT];
 
        /* add sysfs attributes */
        result = sysfs_create_group(&device->dev.kobj, &pcc_attr_group);