[PATCH 9/9] add platform devices for firmware brightness registers

From: Kenneth Chan
Date: Fri Aug 21 2020 - 14:17:06 EST

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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
platform devices 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@xxxxxxxxx>
---
drivers/platform/x86/panasonic-laptop.c | 109 ++++++++++++++++++++++++
1 file changed, 109 insertions(+)

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index 6355d60dc3eb..6388c3c705a6 100644
--- 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@xxxxxxxxx>
+ * -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@xxxxxxxxxx>");
MODULE_AUTHOR("David Bronaugh <dbronaugh@xxxxxxxxxxxxxx>");
MODULE_AUTHOR("Harald Welte <laforge@xxxxxxxxxxxx>");
@@ -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);
--
2.17.5

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