Input: atmel_mxt_ts - implement T44 message handling

maXTouch chips allow the reading of multiple messages in a single I2C
transaction, which reduces bus overhead and improves performance/latency. The
number of messages available to be read is given by the value in the T44
object which is located directly before the T5 object.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 159 insertions, 32 deletions

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 699de552a6d8..c6dfd0af6365 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -244,12 +244,15 @@ struct mxt_data {
         unsigned int max_y;
         bool in_bootloader;
         u16 mem_size;
+        u8 max_reportid;
         u32 config_crc;
         u32 info_crc;
         u8 bootloader_addr;
         u8 *msg_buf;
         u8 t6_status;
         bool update_input;
+        u8 last_message_count;
+        u8 num_touchids;
 
         /* Cached parameters from object table */
         u16 T5_address;
@@ -260,6 +263,7 @@ struct mxt_data {
         u8 T9_reportid_min;
         u8 T9_reportid_max;
         u8 T19_reportid;
+        u16 T44_address;
 
         /* for fw update in bootloader */
         struct completion bl_completion;
@@ -795,30 +799,142 @@ static int mxt_proc_message(struct mxt_data *data, u8 *message)
         return 1;
 }
 
-static int mxt_read_and_process_message(struct mxt_data *data)
+static int mxt_read_and_process_messages(struct mxt_data *data, u8 count)
 {
         struct device *dev = &data->client->dev;
         int ret;
+        int i;
+        u8 num_valid = 0;
+
+        /* Safety check for msg_buf */
+        if (count > data->max_reportid)
+                return -EINVAL;
 
+        /* Process remaining messages if necessary */
         ret = __mxt_read_reg(data->client, data->T5_address,
-                                data->T5_msg_size, data->msg_buf);
+                                data->T5_msg_size * count, data->msg_buf);
         if (ret) {
-                dev_err(dev, "Error %d reading message\n", ret);
+                dev_err(dev, "Failed to read %u messages (%d)\n", count, ret);
                 return ret;
         }
 
-        return mxt_proc_message(data, data->msg_buf);
+        for (i = 0;  i < count; i++) {
+                ret = mxt_proc_message(data,
+                        data->msg_buf + data->T5_msg_size * i);
+
+                if (ret == 1)
+                        num_valid++;
+        }
+
+        /* return number of messages read */
+        return num_valid;
 }
 
-static irqreturn_t mxt_process_messages_until_invalid(struct mxt_data *data)
+static irqreturn_t mxt_process_messages_t44(struct mxt_data *data)
 {
+        struct device *dev = &data->client->dev;
         int ret;
+        u8 count, num_left;
 
-        do {
-                ret = mxt_read_and_process_message(data);
+        /* Read T44 and T5 together */
+        ret = __mxt_read_reg(data->client, data->T44_address,
+                data->T5_msg_size + 1, data->msg_buf);
+        if (ret) {
+                dev_err(dev, "Failed to read T44 and T5 (%d)\n", ret);
+                return IRQ_NONE;
+        }
+
+        count = data->msg_buf[0];
+
+        if (count == 0) {
+                dev_warn(dev, "Interrupt triggered but zero messages\n");
+                return IRQ_NONE;
+        } else if (count > data->max_reportid) {
+                dev_err(dev, "T44 count %d exceeded max report id\n", count);
+                count = data->max_reportid;
+        }
+
+        /* Process first message */
+        ret = mxt_proc_message(data, data->msg_buf + 1);
+        if (ret < 0) {
+                dev_warn(dev, "Unexpected invalid message\n");
+                return IRQ_NONE;
+        }
+
+        num_left = count - 1;
+
+        /* Process remaining messages if necessary */
+        if (num_left) {
+                ret = mxt_read_and_process_messages(data, num_left);
                 if (ret < 0)
+                        goto end;
+                else if (ret != num_left)
+                        dev_warn(dev, "Unexpected invalid message\n");
+        }
+
+end:
+        if (data->update_input) {
+                mxt_input_sync(data);
+                data->update_input = false;
+        }
+
+        return IRQ_HANDLED;
+}
+
+static int mxt_process_messages_until_invalid(struct mxt_data *data)
+{
+        struct device *dev = &data->client->dev;
+        int count, read;
+        u8 tries = 2;
+
+        count = data->max_reportid;
+
+        /* Read messages until we force an invalid */
+        do {
+                read = mxt_read_and_process_messages(data, count);
+                if (read < count)
+                        return 0;
+        } while (--tries);
+
+        if (data->update_input) {
+                mxt_input_sync(data);
+                data->update_input = false;
+        }
+
+        dev_err(dev, "CHG pin isn't cleared\n");
+        return -EBUSY;
+}
+
+static irqreturn_t mxt_process_messages(struct mxt_data *data)
+{
+        int total_handled, num_handled;
+        u8 count = data->last_message_count;
+
+        if (count < 1 || count > data->max_reportid)
+                count = 1;
+
+        /* include final invalid message */
+        total_handled = mxt_read_and_process_messages(data, count + 1);
+        if (total_handled < 0)
+                return IRQ_NONE;
+        /* if there were invalid messages, then we are done */
+        else if (total_handled <= count)
+                goto update_count;
+
+        /* keep reading two msgs until one is invalid or reportid limit */
+        do {
+                num_handled = mxt_read_and_process_messages(data, 2);
+                if (num_handled < 0)
                         return IRQ_NONE;
-        } while (ret > 0);
+
+                total_handled += num_handled;
+
+                if (num_handled < 2)
+                        break;
+        } while (total_handled < data->num_touchids);
+
+update_count:
+        data->last_message_count = total_handled;
 
         if (data->update_input) {
                 mxt_input_sync(data);
@@ -841,7 +957,11 @@ static irqreturn_t mxt_interrupt(int irq, void *dev_id)
         if (!data->object_table)
                 return IRQ_HANDLED;
 
-        return mxt_process_messages_until_invalid(data);
+        if (data->T44_address) {
+                return mxt_process_messages_t44(data);
+        } else {
+                return mxt_process_messages(data);
+        }
 }
 
 static int mxt_t6_command(struct mxt_data *data, u16 cmd_offset,
@@ -1214,32 +1334,13 @@ release:
         return ret;
 }
 
-static int mxt_make_highchg(struct mxt_data *data)
-{
-        struct device *dev = &data->client->dev;
-        int count = 10;
-        int ret;
-
-        /* Read messages until we force an invalid */
-        do {
-                ret = mxt_read_and_process_message(data);
-                if (ret == 0)
-                        return 0;
-                else if (ret < 0)
-                        return ret;
-        } while (--count);
-
-        dev_err(dev, "CHG pin isn't cleared\n");
-        return -EBUSY;
-}
-
 static int mxt_acquire_irq(struct mxt_data *data)
 {
         int error;
 
         enable_irq(data->irq);
 
-        error = mxt_make_highchg(data);
+        error = mxt_process_messages_until_invalid(data);
         if (error)
                 return error;
 
@@ -1276,6 +1377,8 @@ static void mxt_free_object_table(struct mxt_data *data)
         data->T9_reportid_min = 0;
         data->T9_reportid_max = 0;
         data->T19_reportid = 0;
+        data->T44_address = 0;
+        data->max_reportid = 0;
 }
 
 static int mxt_get_object_table(struct mxt_data *data)
@@ -1329,8 +1432,16 @@ static int mxt_get_object_table(struct mxt_data *data)
 
                 switch (object->type) {
                 case MXT_GEN_MESSAGE_T5:
-                        /* CRC not enabled, therefore don't read last byte */
-                        data->T5_msg_size = mxt_obj_size(object) - 1;
+                        if (data->info.family_id == 0x80) {
+                                /*
+                                 * On mXT224 read and discard unused CRC byte
+                                 * otherwise DMA reads are misaligned
+                                 */
+                                data->T5_msg_size = mxt_obj_size(object);
+                        } else {
+                                /* CRC not enabled, so skip last byte */
+                                data->T5_msg_size = mxt_obj_size(object) - 1;
+                        }
                         data->T5_address = object->start_address;
                 case MXT_GEN_COMMAND_T6:
                         data->T6_reportid = min_id;
@@ -1342,6 +1453,11 @@ static int mxt_get_object_table(struct mxt_data *data)
                 case MXT_TOUCH_MULTI_T9:
                         data->T9_reportid_min = min_id;
                         data->T9_reportid_max = max_id;
+                        data->num_touchids = object->num_report_ids
+                                                * mxt_obj_instances(object);
+                        break;
+                case MXT_SPT_MESSAGECOUNT_T44:
+                        data->T44_address = object->start_address;
                         break;
                 case MXT_SPT_GPIOPWM_T19:
                         data->T19_reportid = min_id;
@@ -1355,7 +1471,18 @@ static int mxt_get_object_table(struct mxt_data *data)
                         data->mem_size = end_address + 1;
         }
 
-        data->msg_buf = kzalloc(data->T5_msg_size, GFP_KERNEL);
+        /* Store maximum reportid */
+        data->max_reportid = reportid;
+
+        /* If T44 exists, T5 position has to be directly after */
+        if (data->T44_address && (data->T5_address != data->T44_address + 1)) {
+                dev_err(&client->dev, "Invalid T44 position\n");
+                error = -EINVAL;
+                goto free_object_table;
+        }
+
+        data->msg_buf = kcalloc(data->max_reportid,
+                                data->T5_msg_size, GFP_KERNEL);
         if (!data->msg_buf) {
                 dev_err(&client->dev, "Failed to allocate message buffer\n");
                 error = -ENOMEM;