[PATCH v2 3/5] platform: surface: Add surface xbl

Jarrett Schultz
2021-11-08T16:45:05Z

Introduce support for the Extensible Boot Loader driver found on the
Surface Duo. Makes device information available to users via sysfs.

Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>

---

Changes in v2:
- Added types.h inclusion and removed unused inclusions
- Minor updates to code and acronym style
- Remove __packed attribute on driver struct
- Use .dev_groups for sysfs
- Added more in-depth description of driver in Kconfig
- Changed target KernelVersion in sysfs documentation

---

.../ABI/testing/sysfs-platform-surface-xbl | 78 +++++++
MAINTAINERS | 2 +
drivers/platform/surface/Kconfig | 12 +
drivers/platform/surface/Makefile | 1 +
drivers/platform/surface/surface-xbl.c | 215 ++++++++++++++++++
5 files changed, 308 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-platform-surface-xbl
create mode 100644 drivers/platform/surface/surface-xbl.c

diff --git a/Documentation/ABI/testing/sysfs-platform-surface-xbl b/Documentation/ABI/testing/sysfs-platform-surface-xbl
new file mode 100644
index 000000000000..2ae047b884d3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-platform-surface-xbl
@@ -0,0 +1,78 @@
+What: /sys/devices/platform/146bfa94.xbl/battery_present
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns whether the battery is present. Valid
+ values are:
+ 0 - battery absent
+ 1 - battery present
+
+What: /sys/devices/platform/146bfa94.xbl/board_id
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns the board id.
+
+What: /sys/devices/platform/146bfa94.xbl/hw_init_retries
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns retries attempted to initialize the
+ discrete hardware circuit.
+
+What: /sys/devices/platform/146bfa94.xbl/is_act_mode
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns whether ACT mode is enabled. Valid values
+ are:
+ 0 - ACT disabled
+ 1 - ACT enabled
+
+ ACT mode is used to run checks and put the device to shipmode
+ at factory.
+
+What: /sys/devices/platform/146bfa94.xbl/is_customer_mode
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns whether the device is in manufacturing
+ mode. Valid values are:
+ 0 - Not in manufacturing mode
+ 1 - In manufacturing mode
+
+What: /sys/devices/platform/146bfa94.xbl/ocp_error_location
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns 0 or which power rail has the OCP error.
+ Valid values are:
+ Bit(s) Meaning
+ 15 More than one OCP error occurred
+ 14-12 PMIC
+ 11-7 SMPS
+ 6-2 LDO
+ 1-0 BOB
+
+What: /sys/devices/platform/146bfa94.xbl/pmic_reset_reason
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns the reason for the reset. Valid values
+ are:
+ 0 - no reason lol
+ 9 - Battery driver triggered
+
+What: /sys/devices/platform/146bfa94.xbl/touch_fw_version
+Date: October 2021
+KernelVersion: 5.16
+Contact: jaschultz@microsoft.com
+Description:
+ Read only. It returns the version of the firmware.
diff --git a/MAINTAINERS b/MAINTAINERS
index 8643546f8fab..d08b68d626f6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12428,7 +12428,9 @@ M: Jarrett Schultz <jaschultz@microsoft.com>
L: linux-arm-msm@vger.kernel.org
L: platform-driver-x86@vger.kernel.org
S: Supported
+F: Documentation/ABI/testing/sysfs-platform-surface-xbl
F: Documentation/devicetree/bindings/platform/microsoft/surface-xbl.yaml
+F: drivers/platform/surface/surface-xbl.c

MICROSOFT SURFACE GPE LID SUPPORT DRIVER
M: Maximilian Luz <luzmaximilian@gmail.com>
diff --git a/drivers/platform/surface/Kconfig b/drivers/platform/surface/Kconfig
index 0d3970e1d144..3a1ced269d96 100644
--- a/drivers/platform/surface/Kconfig
+++ b/drivers/platform/surface/Kconfig
@@ -190,6 +190,18 @@ config SURFACE_PRO3_BUTTON
help
This driver handles the power/home/volume buttons on the Microsoft Surface Pro 3/4 tablet.

+config SURFACE_XBL
+ tristate "Surface XBL Driver"
+ depends on ARM64 || COMPILE_TEST
+ depends on OF
+ help
+ If you say 'Y' to this option, support will be included for the
+ Surface Extensible Boot Loader (XBL) Driver. This driver exposes
+ information about the device through sysfs.
+
+ This driver can also be built as a module. If so, the module
+ will be called surface-xbl.
+
source "drivers/platform/surface/aggregator/Kconfig"

endif # SURFACE_PLATFORMS
diff --git a/drivers/platform/surface/Makefile b/drivers/platform/surface/Makefile
index 32889482de55..0946266a8a73 100644
--- a/drivers/platform/surface/Makefile
+++ b/drivers/platform/surface/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_SURFACE_GPE) += surface_gpe.o
obj-$(CONFIG_SURFACE_HOTPLUG) += surface_hotplug.o
obj-$(CONFIG_SURFACE_PLATFORM_PROFILE) += surface_platform_profile.o
obj-$(CONFIG_SURFACE_PRO3_BUTTON) += surfacepro3_button.o
+obj-$(CONFIG_SURFACE_XBL) += surface-xbl.o
diff --git a/drivers/platform/surface/surface-xbl.c b/drivers/platform/surface/surface-xbl.c
new file mode 100644
index 000000000000..9ecec4e55a4d
--- /dev/null
+++ b/drivers/platform/surface/surface-xbl.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Surface eXtensible Boot Loader (XBL)
+ *
+ * Copyright (C) 2021 Microsoft Corporation
+ * Author: Jarrett Schultz <jaschultz@microsoft.com>
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#define SURFACE_XBL_MAX_VERSION_LEN 16
+#define SURFACE_XBL_BOARD_ID 0
+#define SURFACE_XBL_BATTERY_PRESENT 1
+#define SURFACE_XBL_HW_INIT_RETRIES 2
+#define SURFACE_XBL_IS_CUSTOMER_MODE 3
+#define SURFACE_XBL_IS_ACT_MODE 4
+#define SURFACE_XBL_PMIC_RESET_REASON 5
+#define SURFACE_XBL_TOUCH_FW_VERSION 6
+#define SURFACE_XBL_OCP_ERROR_LOCATION \
+ (SURFACE_XBL_TOUCH_FW_VERSION + \
+ SURFACE_XBL_MAX_VERSION_LEN)
+
+struct surface_xbl {
+ struct device *dev;
+ void __iomem *regs;
+
+ u8 board_id;
+ u8 battery_present;
+ u8 hw_init_retries;
+ u8 is_customer_mode;
+ u8 is_act_mode;
+ u8 pmic_reset_reason;
+ char touch_fw_version[SURFACE_XBL_MAX_VERSION_LEN];
+ u16 ocp_error_location;
+};
+
+static ssize_t
+board_id_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", sxbl->board_id);
+}
+static DEVICE_ATTR_RO(board_id);
+
+static ssize_t
+battery_present_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", sxbl->battery_present);
+}
+static DEVICE_ATTR_RO(battery_present);
+
+static ssize_t
+hw_init_retries_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", sxbl->hw_init_retries);
+}
+static DEVICE_ATTR_RO(hw_init_retries);
+
+static ssize_t
+is_customer_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", sxbl->is_customer_mode);
+}
+static DEVICE_ATTR_RO(is_customer_mode);
+
+static ssize_t
+is_act_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", sxbl->is_act_mode);
+}
+static DEVICE_ATTR_RO(is_act_mode);
+
+static ssize_t
+pmic_reset_reason_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", sxbl->pmic_reset_reason);
+}
+static DEVICE_ATTR_RO(pmic_reset_reason);
+
+static ssize_t
+touch_fw_version_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "0x%s\n", sxbl->touch_fw_version);
+}
+static DEVICE_ATTR_RO(touch_fw_version);
+
+static ssize_t
+ocp_error_location_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct surface_xbl *sxbl = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", sxbl->ocp_error_location);
+}
+static DEVICE_ATTR_RO(ocp_error_location);
+
+static struct attribute *xbl_attrs[] = {
+ &dev_attr_board_id.attr,
+ &dev_attr_battery_present.attr,
+ &dev_attr_hw_init_retries.attr,
+ &dev_attr_is_customer_mode.attr,
+ &dev_attr_is_act_mode.attr,
+ &dev_attr_pmic_reset_reason.attr,
+ &dev_attr_touch_fw_version.attr,
+ &dev_attr_ocp_error_location.attr,
+ NULL
+};
+
+static const struct attribute_group xbl_attr_group = {
+ .attrs = xbl_attrs,
+};
+
+const struct attribute_group *xbl_sysfs_groups[] = {
+ &xbl_attr_group,
+ NULL
+};
+
+static u8 surface_xbl_readb(void __iomem *base, u32 offset)
+{
+ return readb(base + offset);
+}
+
+static u16 surface_xbl_readw(void __iomem *base, u32 offset)
+{
+ return readw(base + offset);
+}
+
+static int surface_xbl_probe(struct platform_device *pdev)
+{
+ struct surface_xbl *sxbl;
+ struct device *dev;
+ void __iomem *regs;
+ int index;
+
+ dev = &pdev->dev;
+ sxbl = devm_kzalloc(dev, sizeof(*sxbl), GFP_KERNEL);
+ if (!sxbl)
+ return -ENOMEM;
+
+ sxbl->dev = dev;
+
+ regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(regs))
+ return PTR_ERR(regs);
+
+ sxbl->regs = regs;
+
+ platform_set_drvdata(pdev, sxbl);
+
+ sxbl->board_id = surface_xbl_readb(sxbl->regs,
+ SURFACE_XBL_BOARD_ID);
+ sxbl->battery_present = surface_xbl_readb(sxbl->regs,
+ SURFACE_XBL_BATTERY_PRESENT);
+ sxbl->hw_init_retries = surface_xbl_readb(sxbl->regs,
+ SURFACE_XBL_HW_INIT_RETRIES);
+ sxbl->is_customer_mode = surface_xbl_readb(sxbl->regs,
+ SURFACE_XBL_IS_CUSTOMER_MODE);
+ sxbl->is_act_mode = surface_xbl_readb(sxbl->regs,
+ SURFACE_XBL_IS_ACT_MODE);
+ sxbl->pmic_reset_reason = surface_xbl_readb(sxbl->regs,
+ SURFACE_XBL_PMIC_RESET_REASON);
+
+ for (index = 0; index < SURFACE_XBL_MAX_VERSION_LEN; index++)
+ sxbl->touch_fw_version[index] = surface_xbl_readb(sxbl->regs,
+ SURFACE_XBL_TOUCH_FW_VERSION + index);
+
+ sxbl->ocp_error_location = surface_xbl_readw(sxbl->regs,
+ SURFACE_XBL_OCP_ERROR_LOCATION);
+
+ return 0;
+}
+
+static int surface_xbl_remove(struct platform_device *pdev)
+{
+ return 0;
+}
+
+static const struct of_device_id surface_xbl_of_match[] = {
+ {
+ .compatible = "microsoft,sm8150-surface-duo-xbl"
+ },
+ { }
+};
+MODULE_DEVICE_TABLE(of, surface_xbl_of_match);
+
+static struct platform_driver surface_xbl_driver = {
+ .driver = {
+ .name = "surface-xbl",
+ .of_match_table = surface_xbl_of_match,
+ .dev_groups = xbl_sysfs_groups
+ },
+ .probe = surface_xbl_probe,
+ .remove = surface_xbl_remove
+};
+module_platform_driver(surface_xbl_driver);
+
+MODULE_AUTHOR("Jarrett Schultz <jaschultz@microsoft.com>");
+MODULE_DESCRIPTION("Surface Extensible Bootloader");
+MODULE_LICENSE("GPL");
--
2.25.1