--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Platform driver for OXP Handhelds that expose fan reading and control
+ * via hwmon sysfs.
+ *
+ * All boards have the same DMI strings and they are told appart by the
+ * boot cpu vendor (Intel/AMD). Currently only AMD boards are supported
+ * but the code is made to be simple to add other handheld boards in the
+ * future.
+ * Fan control is provided via pwm interface in the range [0-255]. AMD
+ * boards use [0-100] as range in the EC, the written value is scaled to
+ * accommodate for that.
+ *
+ * Copyright (C) 2022 Joaquín I. Aramendía <samsagax@gmail.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/dev_printk.h>
+#include <linux/dmi.h>
+#include <linux/hwmon.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/processor.h>
+
+/* Handle ACPI lock mechanism */
+static u32 oxp_mutex;
+
+#define ACPI_LOCK_DELAY_MS 500
+
+static bool lock_global_acpi_lock(void)
+{
+ return ACPI_SUCCESS(acpi_acquire_global_lock(ACPI_LOCK_DELAY_MS, &oxp_mutex));
+}
+
+static bool unlock_global_acpi_lock(void)
+{
+ return ACPI_SUCCESS(acpi_release_global_lock(oxp_mutex));
+}
+
+#define OXP_SENSOR_FAN_REG 0x76 /* Fan reading is 2 registers long */
+#define OXP_SENSOR_PWM_ENABLE_REG 0x4A /* PWM enable is 1 register long */
+#define OXP_SENSOR_PWM_REG 0x4B /* PWM reading is 1 register long */
+
+static const struct dmi_system_id dmi_table[] = {
+ {
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "ONE-NETBOOK"),
+ DMI_EXACT_MATCH(DMI_BOARD_NAME, "ONE XPLAYER"),
+ },
+ },
+ {},
+};
+
+/* Helper functions to handle EC read/write */
+static int read_from_ec(u8 reg, int size, long *val)
+{
+ int i;
+ int ret;
+ u8 buffer;
+
+ if (!lock_global_acpi_lock())
+ return -EBUSY;
+
+ *val = 0;
+ for (i = 0; i < size; i++) {
+ ret = ec_read(reg + i, &buffer);
+ if (ret)
+ return ret;
+ *val <<= i * 8;
+ *val += buffer;
+ }
+
+ if (!unlock_global_acpi_lock())
+ return -EBUSY;
+
+ return 0;
+}
+
+static int write_to_ec(const struct device *dev, u8 reg, u8 value)
+{
+ int ret;
+
+ if (!lock_global_acpi_lock())
+ return -EBUSY;
+
+ ret = ec_write(reg, value);
+
+ if (!unlock_global_acpi_lock())
+ return -EBUSY;
+
+ return ret;
+}
+
+static int oxp_pwm_enable(const struct device *dev)
+{
+ return write_to_ec(dev, OXP_SENSOR_PWM_ENABLE_REG, 0x01);
+}
+
+static int oxp_pwm_disable(const struct device *dev)
+{
+ return write_to_ec(dev, OXP_SENSOR_PWM_ENABLE_REG, 0x00);
+}
+
+/* Callbacks for hwmon interface */
+static umode_t oxp_ec_hwmon_is_visible(const void *drvdata,
+ enum hwmon_sensor_types type, u32 attr, int channel)
+{
+ switch (type) {
+ case hwmon_fan:
+ return 0444;
+ case hwmon_pwm:
+ return 0644;
+ default:
+ return 0;
+ }
+}
+
+static int oxp_platform_read(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long *val)
+{
+ int ret;
+
+ switch (type) {
+ case hwmon_fan:
+ switch (attr) {
+ case hwmon_fan_input:
+ return read_from_ec(OXP_SENSOR_FAN_REG, 2, val);
+ default:
+ break;
+ }
+ break;
+ case hwmon_pwm:
+ switch (attr) {
+ case hwmon_pwm_input:
+ ret = read_from_ec(OXP_SENSOR_PWM_REG, 2, val);
+ if (ret)
+ return ret;
+ *val = (*val * 255) / 100;
+ return 0;
+ case hwmon_pwm_enable:
+ return read_from_ec(OXP_SENSOR_PWM_ENABLE_REG, 1, val);
+ default:
+ break;
+ }
+ break;
+ default:
+ break;
+ }
+ return -EOPNOTSUPP;
+}
+
+static int oxp_platform_write(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long val)
+{
+ switch (type) {
+ case hwmon_pwm:
+ switch (attr) {
+ case hwmon_pwm_enable:
+ if (val == 1)
+ return oxp_pwm_enable(dev);
+ else if (val == 0)
+ return oxp_pwm_disable(dev);
+ return -EINVAL;
+ case hwmon_pwm_input:
+ if (val < 0 || val > 255)
+ return -EINVAL;
+ val = (val * 100) / 255;
+ return write_to_ec(dev, OXP_SENSOR_PWM_REG, val);
+ default:
+ break;
+ }
+ break;
+ default:
+ break;
+ }
+ return -EOPNOTSUPP;
+}
+
+/* Known sensors in the OXP EC controllers */
+static const struct hwmon_channel_info *oxp_platform_sensors[] = {
+ HWMON_CHANNEL_INFO(fan,
+ HWMON_F_INPUT),
+ HWMON_CHANNEL_INFO(pwm,
+ HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
+ NULL,
+};
+
+static const struct hwmon_ops oxp_ec_hwmon_ops = {
+ .is_visible = oxp_ec_hwmon_is_visible,
+ .read = oxp_platform_read,
+ .write = oxp_platform_write,
+};
+
+static const struct hwmon_chip_info oxp_ec_chip_info = {
+ .ops = &oxp_ec_hwmon_ops,
+ .info = oxp_platform_sensors,
+};
+
+/* Initialization logic */
+static int oxp_platform_probe(struct platform_device *pdev)
+{
+ const struct dmi_system_id *dmi_entry;
+ struct device *dev = &pdev->dev;
+ struct device *hwdev;
+
+ /*
+ * Have to check for AMD processor here because DMI strings are the
+ * same between Intel and AMD boards, the only way to tell them appart
+ * is the CPU.
+ * Intel boards seem to have different EC registers and values to
+ * read/write.
+ */
+ dmi_entry = dmi_first_match(dmi_table);
+ if (!dmi_entry || boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
+ return -ENODEV;
+
+ hwdev = devm_hwmon_device_register_with_info(dev, "oxpec", NULL,
+ &oxp_ec_chip_info, NULL);
+
+ return PTR_ERR_OR_ZERO(hwdev);
+}
+
+static struct platform_driver oxp_platform_driver = {
+ .driver = {
+ .name = "oxp-platform",
+ },
+ .probe = oxp_platform_probe,
+};
+
+static struct platform_device *oxp_platform_device;
+
+static int __init oxp_platform_init(void)
+{
+ oxp_platform_device =
+ platform_create_bundle(&oxp_platform_driver,
+ oxp_platform_probe, NULL, 0, NULL, 0);
+
+ return PTR_ERR_OR_ZERO(oxp_platform_device);
+}
+
+static void __exit oxp_platform_exit(void)
+{
+ platform_device_unregister(oxp_platform_device);
+ platform_driver_unregister(&oxp_platform_driver);
+}
+
+MODULE_DEVICE_TABLE(dmi, dmi_table);
+
+module_init(oxp_platform_init);
+module_exit(oxp_platform_exit);
+
+MODULE_AUTHOR("Joaquín Ignacio Aramendía <samsagax@gmail.com>");
+MODULE_DESCRIPTION("Platform driver that handles EC sensors of OneXPlayer devices");
+MODULE_LICENSE("GPL");
projects / platform / kernel / linux-starfive.git / commitdiff