Input: elantech - add support for SMBus devices

Many of the Elantech devices are connected through PS/2 and a different
bus (SMBus or plain I2C).

To not break any existing device, we only enable SMBus based
on a module parameter. If some laptops require the quirk to
be set, we will have to rely on a list of PNPIds or MDI matching
to individually expose those hardware over SMBus.
the parameter mentioned above is elantech_smbus from the psmouse
module.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

6 files changed, 246 insertions, 11 deletions

diff --git a/drivers/input/mouse/Kconfig b/drivers/input/mouse/Kconfig
index 89ebb8f39fee..f27f23f2d99a 100644
--- a/drivers/input/mouse/Kconfig
+++ b/drivers/input/mouse/Kconfig
@@ -133,6 +133,18 @@ config MOUSE_PS2_ELANTECH
 
           If unsure, say N.
 
+config MOUSE_PS2_ELANTECH_SMBUS
+        bool "Elantech PS/2 SMbus companion" if EXPERT
+        default y
+        depends on MOUSE_PS2 && MOUSE_PS2_ELANTECH
+        depends on I2C=y || I2C=MOUSE_PS2
+        select MOUSE_PS2_SMBUS
+        help
+          Say Y here if you have a Elantech touchpad connected to
+          to an SMBus, but enumerated through PS/2.
+
+          If unsure, say Y.
+
 config MOUSE_PS2_SENTELIC
         bool "Sentelic Finger Sensing Pad PS/2 protocol extension"
         depends on MOUSE_PS2
diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index a2a14a31edb5..510e7c0622d3 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -14,13 +14,16 @@
 #include <linux/dmi.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/i2c.h>
 #include <linux/input.h>
 #include <linux/input/mt.h>
+#include <linux/platform_device.h>
 #include <linux/serio.h>
 #include <linux/libps2.h>
 #include <asm/unaligned.h>
 #include "psmouse.h"
 #include "elantech.h"
+#include "elan_i2c.h"
 
 #define elantech_debug(fmt, ...)                                        \
         do {                                                            \
@@ -1084,7 +1087,8 @@ static unsigned int elantech_convert_res(unsigned int val)
 
 static int elantech_get_resolution_v4(struct psmouse *psmouse,
                                       unsigned int *x_res,
-                                      unsigned int *y_res)
+                                      unsigned int *y_res,
+                                      unsigned int *bus)
 {
         unsigned char param[3];
 
@@ -1093,6 +1097,7 @@ static int elantech_get_resolution_v4(struct psmouse *psmouse,
 
         *x_res = elantech_convert_res(param[1] & 0x0f);
         *y_res = elantech_convert_res((param[1] & 0xf0) >> 4);
+        *bus = param[2];
 
         return 0;
 }
@@ -1474,6 +1479,12 @@ static void elantech_disconnect(struct psmouse *psmouse)
 {
         struct elantech_data *etd = psmouse->private;
 
+        /*
+         * We might have left a breadcrumb when trying to
+         * set up SMbus companion.
+         */
+        psmouse_smbus_cleanup(psmouse);
+
         if (etd->tp_dev)
                 input_unregister_device(etd->tp_dev);
         sysfs_remove_group(&psmouse->ps2dev.serio->dev.kobj,
@@ -1659,6 +1670,8 @@ static int elantech_query_info(struct psmouse *psmouse,
 {
         unsigned char param[3];
 
+        memset(info, 0, sizeof(*info));
+
         /*
          * Do the version query again so we can store the result
          */
@@ -1717,7 +1730,8 @@ static int elantech_query_info(struct psmouse *psmouse,
         if (info->hw_version == 4) {
                 if (elantech_get_resolution_v4(psmouse,
                                                &info->x_res,
-                                               &info->y_res)) {
+                                               &info->y_res,
+                                               &info->bus)) {
                         psmouse_warn(psmouse,
                                      "failed to query resolution data.\n");
                 }
@@ -1726,6 +1740,129 @@ static int elantech_query_info(struct psmouse *psmouse,
         return 0;
 }
 
+#if defined(CONFIG_MOUSE_PS2_ELANTECH_SMBUS)
+
+/*
+ * The newest Elantech device can use a secondary bus (over SMBus) which
+ * provides a better bandwidth and allow a better control of the touchpads.
+ * This is used to decide if we need to use this bus or not.
+ */
+enum {
+        ELANTECH_SMBUS_NOT_SET = -1,
+        ELANTECH_SMBUS_OFF,
+        ELANTECH_SMBUS_ON,
+};
+
+static int elantech_smbus = IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_SMBUS) ?
+                ELANTECH_SMBUS_NOT_SET : ELANTECH_SMBUS_OFF;
+module_param_named(elantech_smbus, elantech_smbus, int, 0644);
+MODULE_PARM_DESC(elantech_smbus, "Use a secondary bus for the Elantech device.");
+
+static int elantech_create_smbus(struct psmouse *psmouse,
+                                 struct elantech_device_info *info,
+                                 bool leave_breadcrumbs)
+{
+        const struct property_entry i2c_properties[] = {
+                PROPERTY_ENTRY_BOOL("elan,trackpoint"),
+                { },
+        };
+        struct i2c_board_info smbus_board = {
+                I2C_BOARD_INFO("elan_i2c", 0x15),
+                .flags = I2C_CLIENT_HOST_NOTIFY,
+        };
+
+        if (info->has_trackpoint)
+                smbus_board.properties = i2c_properties;
+
+        return psmouse_smbus_init(psmouse, &smbus_board, NULL, 0,
+                                  leave_breadcrumbs);
+}
+
+/**
+ * elantech_setup_smbus - called once the PS/2 devices are enumerated
+ * and decides to instantiate a SMBus InterTouch device.
+ */
+static int elantech_setup_smbus(struct psmouse *psmouse,
+                                struct elantech_device_info *info,
+                                bool leave_breadcrumbs)
+{
+        int error;
+
+        if (elantech_smbus == ELANTECH_SMBUS_OFF)
+                return -ENXIO;
+
+        if (elantech_smbus == ELANTECH_SMBUS_NOT_SET) {
+                /*
+                 * FIXME:
+                 * constraint the I2C capable devices by using FW version,
+                 * board version, or by using DMI matching
+                 */
+                return -ENXIO;
+        }
+
+        psmouse_info(psmouse, "Trying to set up SMBus access\n");
+
+        error = elantech_create_smbus(psmouse, info, leave_breadcrumbs);
+        if (error) {
+                if (error == -EAGAIN)
+                        psmouse_info(psmouse, "SMbus companion is not ready yet\n");
+                else
+                        psmouse_err(psmouse, "unable to create intertouch device\n");
+
+                return error;
+        }
+
+        return 0;
+}
+
+static bool elantech_use_host_notify(struct psmouse *psmouse,
+                                     struct elantech_device_info *info)
+{
+        switch (info->bus) {
+        case ETP_BUS_PS2_ONLY:
+                /* expected case */
+                break;
+        case ETP_BUS_SMB_ALERT_ONLY:
+                /* fall-through  */
+        case ETP_BUS_PS2_SMB_ALERT:
+                psmouse_dbg(psmouse, "Ignoring SMBus provider through alert protocol.\n");
+                break;
+        case ETP_BUS_SMB_HST_NTFY_ONLY:
+                /* fall-through  */
+        case ETP_BUS_PS2_SMB_HST_NTFY:
+                return true;
+        default:
+                psmouse_dbg(psmouse,
+                            "Ignoring SMBus bus provider %d.\n",
+                            info->bus);
+        }
+
+        return false;
+}
+
+int elantech_init_smbus(struct psmouse *psmouse)
+{
+        struct elantech_device_info info;
+        int error = -EINVAL;
+
+        psmouse_reset(psmouse);
+
+        error = elantech_query_info(psmouse, &info);
+        if (error)
+                goto init_fail;
+
+        if (info.hw_version < 4) {
+                error = -ENXIO;
+                goto init_fail;
+        }
+
+        return elantech_create_smbus(psmouse, &info, false);
+ init_fail:
+        psmouse_reset(psmouse);
+        return error;
+}
+#endif /* CONFIG_MOUSE_PS2_ELANTECH_SMBUS */
+
 /*
  * Initialize the touchpad and create sysfs entries
  */
@@ -1734,7 +1871,7 @@ static int elantech_setup_ps2(struct psmouse *psmouse,
 {
         struct elantech_data *etd;
         int i;
-        int error;
+        int error = -EINVAL;
         struct input_dev *tp_dev;
 
         psmouse->private = etd = kzalloc(sizeof(*etd), GFP_KERNEL);
@@ -1821,7 +1958,7 @@ static int elantech_setup_ps2(struct psmouse *psmouse,
         return error;
 }
 
-int elantech_init(struct psmouse *psmouse)
+int elantech_init_ps2(struct psmouse *psmouse)
 {
         struct elantech_device_info info;
         int error = -EINVAL;
@@ -1841,3 +1978,46 @@ int elantech_init(struct psmouse *psmouse)
         psmouse_reset(psmouse);
         return error;
 }
+
+int elantech_init(struct psmouse *psmouse)
+{
+        struct elantech_device_info info;
+        int error = -EINVAL;
+
+        psmouse_reset(psmouse);
+
+        error = elantech_query_info(psmouse, &info);
+        if (error)
+                goto init_fail;
+
+#if defined(CONFIG_MOUSE_PS2_ELANTECH_SMBUS)
+
+        if (elantech_use_host_notify(psmouse, &info)) {
+                if (!IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_SMBUS) ||
+                    !IS_ENABLED(CONFIG_MOUSE_PS2_ELANTECH_SMBUS)) {
+                        psmouse_warn(psmouse,
+                                     "The touchpad can support a better bus than the too old PS/2 protocol. "
+                                     "Make sure MOUSE_PS2_ELANTECH_SMBUS and MOUSE_ELAN_I2C_SMBUS are enabled to get a better touchpad experience.\n");
+                }
+                error = elantech_setup_smbus(psmouse, &info, true);
+                if (!error)
+                        return PSMOUSE_ELANTECH_SMBUS;
+        }
+
+#endif /* CONFIG_MOUSE_PS2_ELANTECH_SMBUS */
+
+        error = elantech_setup_ps2(psmouse, &info);
+        if (error < 0) {
+                /*
+                 * Not using any flavor of Elantech support, so clean up
+                 * SMbus breadcrumbs, if any.
+                 */
+                psmouse_smbus_cleanup(psmouse);
+                goto init_fail;
+        }
+
+        return PSMOUSE_ELANTECH;
+ init_fail:
+        psmouse_reset(psmouse);
+        return error;
+}
diff --git a/drivers/input/mouse/elantech.h b/drivers/input/mouse/elantech.h
index 851df4ce6232..f9b1c485e8d9 100644
--- a/drivers/input/mouse/elantech.h
+++ b/drivers/input/mouse/elantech.h
@@ -107,6 +107,15 @@
 #define ETP_WEIGHT_VALUE                5
 
 /*
+ * Bus information on 3rd byte of query ETP_RESOLUTION_QUERY(0x04)
+ */
+#define ETP_BUS_PS2_ONLY                0
+#define ETP_BUS_SMB_ALERT_ONLY          1
+#define ETP_BUS_SMB_HST_NTFY_ONLY       2
+#define ETP_BUS_PS2_SMB_ALERT           3
+#define ETP_BUS_PS2_SMB_HST_NTFY        4
+
+/*
  * The base position for one finger, v4 hardware
  */
 struct finger_pos {
@@ -122,6 +131,7 @@ struct elantech_device_info {
         unsigned int fw_version;
         unsigned int x_res;
         unsigned int y_res;
+        unsigned int bus;
         bool paritycheck;
         bool jumpy_cursor;
         bool reports_pressure;
@@ -156,6 +166,7 @@ struct elantech_data {
 
 #ifdef CONFIG_MOUSE_PS2_ELANTECH
 int elantech_detect(struct psmouse *psmouse, bool set_properties);
+int elantech_init_ps2(struct psmouse *psmouse);
 int elantech_init(struct psmouse *psmouse);
 #else
 static inline int elantech_detect(struct psmouse *psmouse, bool set_properties)
@@ -166,6 +177,19 @@ static inline int elantech_init(struct psmouse *psmouse)
 {
         return -ENOSYS;
 }
+static inline int elantech_init_ps2(struct psmouse *psmouse)
+{
+        return -ENOSYS;
+}
 #endif /* CONFIG_MOUSE_PS2_ELANTECH */
 
+#if defined(CONFIG_MOUSE_PS2_ELANTECH_SMBUS)
+int elantech_init_smbus(struct psmouse *psmouse);
+#else
+static inline int elantech_init_smbus(struct psmouse *psmouse)
+{
+        return -ENOSYS;
+}
+#endif /* CONFIG_MOUSE_PS2_ELANTECH_SMBUS */
+
 #endif
diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index 8900c3166ebf..5ff5b1952be0 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -856,7 +856,17 @@ static const struct psmouse_protocol psmouse_protocols[] = {
                 .name           = "ETPS/2",
                 .alias          = "elantech",
                 .detect         = elantech_detect,
-                .init           = elantech_init,
+                .init           = elantech_init_ps2,
+        },
+#endif
+#ifdef CONFIG_MOUSE_PS2_ELANTECH_SMBUS
+        {
+                .type           = PSMOUSE_ELANTECH_SMBUS,
+                .name           = "ETSMBus",
+                .alias          = "elantech-smbus",
+                .detect         = elantech_detect,
+                .init           = elantech_init_smbus,
+                .smbus_companion = true,
         },
 #endif
 #ifdef CONFIG_MOUSE_PS2_SENTELIC
@@ -1158,8 +1168,13 @@ static int psmouse_extensions(struct psmouse *psmouse,
         /* Try Elantech touchpad */
         if (max_proto > PSMOUSE_IMEX &&
             psmouse_try_protocol(psmouse, PSMOUSE_ELANTECH,
-                                 &max_proto, set_properties, true)) {
-                return PSMOUSE_ELANTECH;
+                                 &max_proto, set_properties, false)) {
+                if (!set_properties)
+                        return PSMOUSE_ELANTECH;
+
+                ret = elantech_init(psmouse);
+                if (ret >= 0)
+                        return ret;
         }
 
         if (max_proto > PSMOUSE_IMEX) {
diff --git a/drivers/input/mouse/psmouse-smbus.c b/drivers/input/mouse/psmouse-smbus.c
index c7ac24d119c1..c8a3b1f35ce3 100644
--- a/drivers/input/mouse/psmouse-smbus.c
+++ b/drivers/input/mouse/psmouse-smbus.c
@@ -237,10 +237,13 @@ int psmouse_smbus_init(struct psmouse *psmouse,
         smbdev->psmouse = psmouse;
         smbdev->board = *board;
 
-        smbdev->board.platform_data = kmemdup(pdata, pdata_size, GFP_KERNEL);
-        if (!smbdev->board.platform_data) {
-                kfree(smbdev);
-                return -ENOMEM;
+        if (pdata) {
+                smbdev->board.platform_data = kmemdup(pdata, pdata_size,
+                                                      GFP_KERNEL);
+                if (!smbdev->board.platform_data) {
+                        kfree(smbdev);
+                        return -ENOMEM;
+                }
         }
 
         psmouse->private = smbdev;
diff --git a/drivers/input/mouse/psmouse.h b/drivers/input/mouse/psmouse.h
index 71ac50082c8b..dd4ec1f602d7 100644
--- a/drivers/input/mouse/psmouse.h
+++ b/drivers/input/mouse/psmouse.h
@@ -68,6 +68,7 @@ enum psmouse_type {
         PSMOUSE_VMMOUSE,
         PSMOUSE_BYD,
         PSMOUSE_SYNAPTICS_SMBUS,
+        PSMOUSE_ELANTECH_SMBUS,
         PSMOUSE_AUTO            /* This one should always be last */
 };