platform/x86: Add intel_bytcrc_pwrsrc driver

Add a new driver for the power-, wake- and reset-source functionality
of the Bay Trail (BYT) version of the Crystal Cove PMIC.

The main functionality here is detecting which power-sources (USB /
DC in / battery) are active. This is normally exposed to userspace as
a power_supply class charger device with an online sysfs attribute.

But if a charger is online or not is already exposed on BYT-CRC devices
through either an ACPI AC power_supply device, or through a native driver
for the battery charger chip (e.g. a BQ24292i).

So instead of adding duplicate info under the power_supply class this
driver exports the info through debugfs and likewise adds debugfs files
for the reset- and wake-source info / registers.

Despite this driver only exporting debugfs bits it is still useful to
have this driver because it clears the wake- and reset-source registers
after reading them. Not clearing these can have undesirable side-effects.

Specifically if the WAKESRC register contains 0x01 (wake by powerbutton)
on reboot then the firmware on some tablets turns the reboot into
a poweroff. I guess this may be necessary to make long power-presses turn
into a poweroff somehow?

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230303221928.285477-1-hdegoede@redhat.com

diff --git a/drivers/platform/x86/intel/Kconfig b/drivers/platform/x86/intel/Kconfig
index bbbd9e54e9ee05848d08d8677fb3e8fdc37a867b..e9dc0c0210299f09e0c59b6a455192ef1abcd300 100644 (file)
--- a/drivers/platform/x86/intel/Kconfig
+++ b/drivers/platform/x86/intel/Kconfig
@@ -80,6 +80,16 @@ config INTEL_BXTWC_PMIC_TMU
          This driver enables the alarm wakeup functionality in the TMU unit of
          Whiskey Cove PMIC.
 
+config INTEL_BYTCRC_PWRSRC
+       tristate "Intel Bay Trail Crystal Cove power source driver"
+       depends on INTEL_SOC_PMIC
+       help
+         This option adds a power source driver for Crystal Cove PMICs
+         on Intel Bay Trail devices.
+
+         To compile this driver as a module, choose M here: the module
+         will be called intel_bytcrc_pwrsrc.
+
 config INTEL_CHTDC_TI_PWRBTN
        tristate "Intel Cherry Trail Dollar Cove TI power button driver"
        depends on INTEL_SOC_PMIC_CHTDC_TI

diff --git a/drivers/platform/x86/intel/Makefile b/drivers/platform/x86/intel/Makefile
index 411df40404272844d69484855c3a1cb0b16e9d1c..c1d5fe05e3f30cbfe6abd10d10024dd21eba54e3 100644 (file)
--- a/drivers/platform/x86/intel/Makefile
+++ b/drivers/platform/x86/intel/Makefile
@@ -38,6 +38,8 @@ intel_bxtwc_tmu-y                     := bxtwc_tmu.o
 obj-$(CONFIG_INTEL_BXTWC_PMIC_TMU)     += intel_bxtwc_tmu.o
 intel_crystal_cove_charger-y           := crystal_cove_charger.o
 obj-$(CONFIG_X86_ANDROID_TABLETS)      += intel_crystal_cove_charger.o
+intel_bytcrc_pwrsrc-y                  := bytcrc_pwrsrc.o
+obj-$(CONFIG_INTEL_BYTCRC_PWRSRC)      += intel_bytcrc_pwrsrc.o
 intel_chtdc_ti_pwrbtn-y                        := chtdc_ti_pwrbtn.o
 obj-$(CONFIG_INTEL_CHTDC_TI_PWRBTN)    += intel_chtdc_ti_pwrbtn.o
 intel_chtwc_int33fe-y                  := chtwc_int33fe.o

diff --git a/drivers/platform/x86/intel/bytcrc_pwrsrc.c b/drivers/platform/x86/intel/bytcrc_pwrsrc.c
new file mode 100644 (file)
index 0000000..8a022b9
--- /dev/null
+++ b/drivers/platform/x86/intel/bytcrc_pwrsrc.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Power-source driver for Bay Trail Crystal Cove PMIC
+ *
+ * Copyright (c) 2023 Hans de Goede <hdegoede@redhat.com>
+ *
+ * Based on intel_crystalcove_pwrsrc.c from Android kernel sources, which is:
+ * Copyright (C) 2013 Intel Corporation
+ */
+
+#include <linux/debugfs.h>
+#include <linux/mfd/intel_soc_pmic.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define CRYSTALCOVE_SPWRSRC_REG                0x1E
+#define CRYSTALCOVE_RESETSRC0_REG      0x20
+#define CRYSTALCOVE_RESETSRC1_REG      0x21
+#define CRYSTALCOVE_WAKESRC_REG                0x22
+
+struct crc_pwrsrc_data {
+       struct regmap *regmap;
+       struct dentry *debug_dentry;
+       unsigned int resetsrc0;
+       unsigned int resetsrc1;
+       unsigned int wakesrc;
+};
+
+static const char * const pwrsrc_pwrsrc_info[] = {
+       /* bit 0 */ "USB",
+       /* bit 1 */ "DC in",
+       /* bit 2 */ "Battery",
+       NULL,
+};
+
+static const char * const pwrsrc_resetsrc0_info[] = {
+       /* bit 0 */ "SOC reporting a thermal event",
+       /* bit 1 */ "critical PMIC temperature",
+       /* bit 2 */ "critical system temperature",
+       /* bit 3 */ "critical battery temperature",
+       /* bit 4 */ "VSYS under voltage",
+       /* bit 5 */ "VSYS over voltage",
+       /* bit 6 */ "battery removal",
+       NULL,
+};
+
+static const char * const pwrsrc_resetsrc1_info[] = {
+       /* bit 0 */ "VCRIT threshold",
+       /* bit 1 */ "BATID reporting battery removal",
+       /* bit 2 */ "user pressing the power button",
+       NULL,
+};
+
+static const char * const pwrsrc_wakesrc_info[] = {
+       /* bit 0 */ "user pressing the power button",
+       /* bit 1 */ "a battery insertion",
+       /* bit 2 */ "a USB charger insertion",
+       /* bit 3 */ "an adapter insertion",
+       NULL,
+};
+
+static void crc_pwrsrc_log(struct seq_file *seq, const char *prefix,
+                          const char * const *info, unsigned int reg_val)
+{
+       int i;
+
+       for (i = 0; info[i]; i++) {
+               if (reg_val & BIT(i))
+                       seq_printf(seq, "%s by %s\n", prefix, info[i]);
+       }
+}
+
+static int pwrsrc_show(struct seq_file *seq, void *unused)
+{
+       struct crc_pwrsrc_data *data = seq->private;
+       unsigned int reg_val;
+       int ret;
+
+       ret = regmap_read(data->regmap, CRYSTALCOVE_SPWRSRC_REG, &reg_val);
+       if (ret)
+               return ret;
+
+       crc_pwrsrc_log(seq, "System powered", pwrsrc_pwrsrc_info, reg_val);
+       return 0;
+}
+
+static int resetsrc_show(struct seq_file *seq, void *unused)
+{
+       struct crc_pwrsrc_data *data = seq->private;
+
+       crc_pwrsrc_log(seq, "Last shutdown caused", pwrsrc_resetsrc0_info, data->resetsrc0);
+       crc_pwrsrc_log(seq, "Last shutdown caused", pwrsrc_resetsrc1_info, data->resetsrc1);
+       return 0;
+}
+
+static int wakesrc_show(struct seq_file *seq, void *unused)
+{
+       struct crc_pwrsrc_data *data = seq->private;
+
+       crc_pwrsrc_log(seq, "Last wake caused", pwrsrc_wakesrc_info, data->wakesrc);
+       return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(pwrsrc);
+DEFINE_SHOW_ATTRIBUTE(resetsrc);
+DEFINE_SHOW_ATTRIBUTE(wakesrc);
+
+static int crc_pwrsrc_read_and_clear(struct crc_pwrsrc_data *data,
+                                    unsigned int reg, unsigned int *val)
+{
+       int ret;
+
+       ret = regmap_read(data->regmap, reg, val);
+       if (ret)
+               return ret;
+
+       return regmap_write(data->regmap, reg, *val);
+}
+
+static int crc_pwrsrc_probe(struct platform_device *pdev)
+{
+       struct intel_soc_pmic *pmic = dev_get_drvdata(pdev->dev.parent);
+       struct crc_pwrsrc_data *data;
+       int ret;
+
+       data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       data->regmap = pmic->regmap;
+
+       /*
+        * Read + clear resetsrc0/1 and wakesrc now, so that they get
+        * cleared even if the debugfs interface is never used.
+        *
+        * Properly clearing the wakesrc is important, leaving bit 0 of it
+        * set turns reboot into poweroff on some tablets.
+        */
+       ret = crc_pwrsrc_read_and_clear(data, CRYSTALCOVE_RESETSRC0_REG, &data->resetsrc0);
+       if (ret)
+               return ret;
+
+       ret = crc_pwrsrc_read_and_clear(data, CRYSTALCOVE_RESETSRC1_REG, &data->resetsrc1);
+       if (ret)
+               return ret;
+
+       ret = crc_pwrsrc_read_and_clear(data, CRYSTALCOVE_WAKESRC_REG, &data->wakesrc);
+       if (ret)
+               return ret;
+
+       data->debug_dentry = debugfs_create_dir(KBUILD_MODNAME, NULL);
+       debugfs_create_file("pwrsrc", 0444, data->debug_dentry, data, &pwrsrc_fops);
+       debugfs_create_file("resetsrc", 0444, data->debug_dentry, data, &resetsrc_fops);
+       debugfs_create_file("wakesrc", 0444, data->debug_dentry, data, &wakesrc_fops);
+
+       platform_set_drvdata(pdev, data);
+       return 0;
+}
+
+static int crc_pwrsrc_remove(struct platform_device *pdev)
+{
+       struct crc_pwrsrc_data *data = platform_get_drvdata(pdev);
+
+       debugfs_remove_recursive(data->debug_dentry);
+       return 0;
+}
+
+static struct platform_driver crc_pwrsrc_driver = {
+       .probe = crc_pwrsrc_probe,
+       .remove = crc_pwrsrc_remove,
+       .driver = {
+               .name = "crystal_cove_pwrsrc",
+       },
+};
+module_platform_driver(crc_pwrsrc_driver);
+
+MODULE_ALIAS("platform:crystal_cove_pwrsrc");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("Power-source driver for Bay Trail Crystal Cove PMIC");
+MODULE_LICENSE("GPL");