[v2,2/2] Input: ads7846: convert to one message

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index e9a520c9ad69..d6c6a13af4ea 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -64,23 +64,13 @@ 
 
 struct ads7846_buf {
 	u8 cmd;
-	/* This union is a temporary hack. The driver does an in-place
-	 * endianness conversion. This will be cleaned up in the next
-	 * patch.
-	 */
-	union {
-		__be16 data_be16;
-		u16 data;
-	};
+	__be16 data;
 } __attribute__((__packed__));
 
-
-struct ts_event {
-	bool ignore;
-	struct ads7846_buf x;
-	struct ads7846_buf y;
-	struct ads7846_buf z1;
-	struct ads7846_buf z2;
+struct ads7846_buf_layout {
+	unsigned int offset;
+	unsigned int count;
+	unsigned int skip;
 };
 
 /*
@@ -89,12 +79,18 @@  struct ts_event {
  * systems where main memory is not DMA-coherent (most non-x86 boards).
  */
 struct ads7846_packet {
-	struct ts_event tc;
-	struct ads7846_buf read_x_cmd;
-	struct ads7846_buf read_y_cmd;
-	struct ads7846_buf read_z1_cmd;
-	struct ads7846_buf read_z2_cmd;
+	unsigned int count;
+	unsigned int count_skip;
+	unsigned int cmds;
+	unsigned int last_cmd_idx;
+	struct ads7846_buf_layout l[5];
+	struct ads7846_buf *rx;
+	struct ads7846_buf *tx;
+
 	struct ads7846_buf pwrdown_cmd;
+
+	bool ignore;
+	u16 x, y, z1, z2;
 };
 
 struct ads7846 {
@@ -193,7 +189,6 @@  struct ads7846 {
 #define	READ_Y(vref)	(READ_12BIT_DFR(y,  1, vref))
 #define	READ_Z1(vref)	(READ_12BIT_DFR(z1, 1, vref))
 #define	READ_Z2(vref)	(READ_12BIT_DFR(z2, 1, vref))
-
 #define	READ_X(vref)	(READ_12BIT_DFR(x,  1, vref))
 #define	PWRDOWN		(READ_12BIT_DFR(y,  0, 0))	/* LAST */
 
@@ -206,6 +201,21 @@  struct ads7846 {
 #define	REF_ON	(READ_12BIT_DFR(x, 1, 1))
 #define	REF_OFF	(READ_12BIT_DFR(y, 0, 0))
 
+/* Order commands in the most optimal way to reduce Vref switching and
+ * settling time:
+ * Measure:  X; Vref: X+, X-; IN: Y+
+ * Measure:  Y; Vref: Y+, Y-; IN: X+
+ * Measure: Z1; Vref: Y+, X-; IN: X+
+ * Measure: Z2; Vref: Y+, X-; IN: Y-
+ */
+enum ads7846_cmds {
+	ADS7846_X,
+	ADS7846_Y,
+	ADS7846_Z1,
+	ADS7846_Z2,
+	ADS7846_PWDOWN,
+};
+
 static int get_pendown_state(struct ads7846 *ts)
 {
 	if (ts->get_pendown_state)
@@ -696,26 +706,109 @@  static int ads7846_no_filter(void *ads, int data_idx, int *val)
 	return ADS7846_FILTER_OK;
 }
 
-static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m)
+static int ads7846_get_value(struct ads7846_buf *buf)
 {
 	int value;
-	struct spi_transfer *t =
-		list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
-	struct ads7846_buf *buf = t->rx_buf;
 
-	value = be16_to_cpup(&buf->data_be16);
+	value = be16_to_cpup(&buf->data);
 
 	/* enforce ADC output is 12 bits width */
 	return (value >> 3) & 0xfff;
 }
 
-static void ads7846_update_value(struct spi_message *m, int val)
+static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx,
+				u16 val)
+{
+	struct ads7846_packet *packet = ts->packet;
+
+	switch (cmd_idx) {
+	case ADS7846_Y:
+		packet->y = val;
+		break;
+	case ADS7846_X:
+		packet->x = val;
+		break;
+	case ADS7846_Z1:
+		packet->z1 = val;
+		break;
+	case ADS7846_Z2:
+		packet->z2 = val;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+}
+
+static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref)
+{
+	switch (cmd_idx) {
+	case ADS7846_Y:
+		return READ_Y(vref);
+	case ADS7846_X:
+		return READ_X(vref);
+
+	/* 7846 specific commands  */
+	case ADS7846_Z1:
+		return READ_Z1(vref);
+	case ADS7846_Z2:
+		return READ_Z2(vref);
+	case ADS7846_PWDOWN:
+		return PWRDOWN;
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	return 0;
+}
+
+static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx)
+{
+	switch (cmd_idx) {
+	case ADS7846_X:
+	case ADS7846_Y:
+	case ADS7846_Z1:
+	case ADS7846_Z2:
+		return true;
+	case ADS7846_PWDOWN:
+		return false;
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	return false;
+}
+
+static int ads7846_filter(struct ads7846 *ts)
 {
-	struct spi_transfer *t =
-		list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
-	struct ads7846_buf *buf = t->rx_buf;
+	struct ads7846_packet *packet = ts->packet;
+	int action;
+	int val;
+	unsigned int cmd_idx, b;
+
+	packet->ignore = false;
+	for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
 
-	buf->data = val;
+		packet->last_cmd_idx = cmd_idx;
+
+		for (b = l->skip; b < l->count; b++) {
+			val = ads7846_get_value(&packet->rx[l->offset + b]);
+
+			action = ts->filter(ts->filter_data, cmd_idx, &val);
+			if (action == ADS7846_FILTER_REPEAT) {
+				if (b == l->count - 1)
+					return -EAGAIN;
+			} else if (action == ADS7846_FILTER_OK) {
+				ads7846_set_cmd_val(ts, cmd_idx, val);
+				break;
+			} else {
+				packet->ignore = true;
+				return 0;
+			}
+		}
+	}
+
+	return 0;
 }
 
 static void ads7846_read_state(struct ads7846 *ts)
@@ -723,52 +816,26 @@  static void ads7846_read_state(struct ads7846 *ts)
 	struct ads7846_packet *packet = ts->packet;
 	struct spi_message *m;
 	int msg_idx = 0;
-	int val;
-	int action;
 	int error;
 
-	while (msg_idx < ts->msg_count) {
+	packet->last_cmd_idx = 0;
 
+	while (true) {
 		ts->wait_for_sync();
 
 		m = &ts->msg[msg_idx];
 		error = spi_sync(ts->spi, m);
 		if (error) {
 			dev_err(&ts->spi->dev, "spi_sync --> %d\n", error);
-			packet->tc.ignore = true;
+			packet->ignore = true;
 			return;
 		}
 
-		/*
-		 * Last message is power down request, no need to convert
-		 * or filter the value.
-		 */
-		if (msg_idx < ts->msg_count - 1) {
+		error = ads7846_filter(ts);
+		if (error)
+			continue;
 
-			val = ads7846_get_value(ts, m);
-
-			action = ts->filter(ts->filter_data, msg_idx, &val);
-			switch (action) {
-			case ADS7846_FILTER_REPEAT:
-				continue;
-
-			case ADS7846_FILTER_IGNORE:
-				packet->tc.ignore = true;
-				msg_idx = ts->msg_count - 1;
-				continue;
-
-			case ADS7846_FILTER_OK:
-				ads7846_update_value(m, val);
-				packet->tc.ignore = false;
-				msg_idx++;
-				break;
-
-			default:
-				BUG();
-			}
-		} else {
-			msg_idx++;
-		}
+		return;
 	}
 }
 
@@ -778,19 +845,14 @@  static void ads7846_report_state(struct ads7846 *ts)
 	unsigned int Rt;
 	u16 x, y, z1, z2;
 
-	/*
-	 * ads7846_get_value() does in-place conversion (including byte swap)
-	 * from on-the-wire format as part of debouncing to get stable
-	 * readings.
-	 */
-	x = packet->tc.x.data;
-	y = packet->tc.y.data;
+	x = packet->x;
+	y = packet->y;
 	if (ts->model == 7845) {
 		z1 = 0;
 		z2 = 0;
 	} else {
-		z1 = packet->tc.z1.data;
-		z2 = packet->tc.z2.data;
+		z1 = packet->z1;
+		z2 = packet->z2;
 	}
 
 	/* range filtering */
@@ -822,9 +884,9 @@  static void ads7846_report_state(struct ads7846 *ts)
 	 * the maximum. Don't report it to user space, repeat at least
 	 * once more the measurement
 	 */
-	if (packet->tc.ignore || Rt > ts->pressure_max) {
+	if (packet->ignore || Rt > ts->pressure_max) {
 		dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
-			 packet->tc.ignore, Rt);
+			 packet->ignore, Rt);
 		return;
 	}
 
@@ -985,13 +1047,59 @@  static int ads7846_setup_pendown(struct spi_device *spi,
  * Set up the transfers to read touchscreen state; this assumes we
  * use formula #2 for pressure, not #3.
  */
-static void ads7846_setup_spi_msg(struct ads7846 *ts,
+static int ads7846_setup_spi_msg(struct ads7846 *ts,
 				  const struct ads7846_platform_data *pdata)
 {
 	struct spi_message *m = &ts->msg[0];
 	struct spi_transfer *x = ts->xfer;
 	struct ads7846_packet *packet = ts->packet;
 	int vref = pdata->keep_vref_on;
+	unsigned int count, offset = 0;
+	unsigned int cmd_idx, b;
+	unsigned long time;
+	size_t size = 0;
+
+	/* time per bit */
+	time = NSEC_PER_SEC / ts->spi->max_speed_hz;
+
+	count = pdata->settle_delay_usecs * NSEC_PER_USEC / time;
+	packet->count_skip = DIV_ROUND_UP(count, 24);
+
+	if (ts->debounce_max && ts->debounce_rep)
+		/* ads7846_debounce_filter() is making ts->debounce_rep + 2
+		 * reads. So we need to get all samples for normal case. */
+		packet->count = ts->debounce_rep + 2;
+	else
+		packet->count = 1;
+
+	if (ts->model == 7846)
+		packet->cmds = 5; /* x, y, z1, z2, pwdown */
+	else
+		packet->cmds = 3; /* x, y, pwdown */
+
+	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+		unsigned int max_count;
+
+		if (ads7846_cmd_need_settle(cmd_idx))
+			max_count = packet->count + packet->count_skip;
+		else
+			max_count = packet->count;
+
+		l->offset = offset;
+		offset += max_count;
+		l->count = max_count;
+		l->skip = packet->count_skip;
+		size += sizeof(*packet->tx) * max_count;
+	}
+
+	packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
+	if (!packet->tx)
+		return -ENOMEM;
+
+	packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
+	if (!packet->rx)
+		return -ENOMEM;
 
 	if (ts->model == 7873) {
 		/*
@@ -1007,117 +1115,20 @@  static void ads7846_setup_spi_msg(struct ads7846 *ts,
 	spi_message_init(m);
 	m->context = ts;
 
-	packet->read_y_cmd.cmd = READ_Y(vref);
-	x->tx_buf = &packet->read_y_cmd;
-	x->rx_buf = &packet->tc.y;
-	x->len = 3;
-	spi_message_add_tail(x, m);
+	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+		u8 cmd = ads7846_get_cmd(cmd_idx, vref);
 
-	/*
-	 * The first sample after switching drivers can be low quality;
-	 * optionally discard it, using a second one after the signals
-	 * have had enough time to stabilize.
-	 */
-	if (pdata->settle_delay_usecs) {
-		x->delay.value = pdata->settle_delay_usecs;
-		x->delay.unit = SPI_DELAY_UNIT_USECS;
-		x++;
-
-		x->tx_buf = &packet->read_y_cmd;
-		x->rx_buf = &packet->tc.y;
-		x->len = 3;
-		spi_message_add_tail(x, m);
+		for (b = 0; b < l->count; b++)
+			packet->tx[l->offset + b].cmd = cmd;
 	}
 
-	ts->msg_count++;
-	m++;
-	spi_message_init(m);
-	m->context = ts;
-
-	/* turn y- off, x+ on, then leave in lowpower */
-	x++;
-	packet->read_x_cmd.cmd = READ_X(vref);
-	x->tx_buf = &packet->read_x_cmd;
-	x->rx_buf = &packet->tc.x;
-	x->len = 3;
+	x->tx_buf = packet->tx;
+	x->rx_buf = packet->rx;
+	x->len = size;
 	spi_message_add_tail(x, m);
 
-	/* ... maybe discard first sample ... */
-	if (pdata->settle_delay_usecs) {
-		x->delay.value = pdata->settle_delay_usecs;
-		x->delay.unit = SPI_DELAY_UNIT_USECS;
-
-		x++;
-		x->tx_buf = &packet->read_x_cmd;
-		x->rx_buf = &packet->tc.x;
-		x->len = 3;
-		spi_message_add_tail(x, m);
-	}
-
-	/* turn y+ off, x- on; we'll use formula #2 */
-	if (ts->model == 7846) {
-		ts->msg_count++;
-		m++;
-		spi_message_init(m);
-		m->context = ts;
-
-		x++;
-		packet->read_z1_cmd.cmd = READ_Z1(vref);
-		x->tx_buf = &packet->read_z1_cmd;
-		x->rx_buf = &packet->tc.z1;
-		x->len = 3;
-		spi_message_add_tail(x, m);
-
-		/* ... maybe discard first sample ... */
-		if (pdata->settle_delay_usecs) {
-			x->delay.value = pdata->settle_delay_usecs;
-			x->delay.unit = SPI_DELAY_UNIT_USECS;
-
-			x++;
-			x->tx_buf = &packet->read_z1_cmd;
-			x->rx_buf = &packet->tc.z1;
-			x->len = 3;
-			spi_message_add_tail(x, m);
-		}
-
-		ts->msg_count++;
-		m++;
-		spi_message_init(m);
-		m->context = ts;
-
-		x++;
-		packet->read_z2_cmd.cmd = READ_Z2(vref);
-		x->tx_buf = &packet->read_z2_cmd;
-		x->rx_buf = &packet->tc.z2;
-		x->len = 3;
-		spi_message_add_tail(x, m);
-
-		/* ... maybe discard first sample ... */
-		if (pdata->settle_delay_usecs) {
-			x->delay.value = pdata->settle_delay_usecs;
-			x->delay.unit = SPI_DELAY_UNIT_USECS;
-
-			x++;
-			x->tx_buf = &packet->read_z2_cmd;
-			x->rx_buf = &packet->tc.z2;
-			x->len = 3;
-			spi_message_add_tail(x, m);
-		}
-	}
-
-	/* power down */
-	ts->msg_count++;
-	m++;
-	spi_message_init(m);
-	m->context = ts;
-
-	x++;
-	packet->pwrdown_cmd.cmd = PWRDOWN;
-	x->tx_buf = &packet->pwrdown_cmd;
-	x->len = 3;
-
-	CS_CHANGE(*x);
-	spi_message_add_tail(x, m);
+	return 0;
 }
 
 #ifdef CONFIG_OF