From e92c27fb5319d8b12f0c291c827e252f0e17afc4 Mon Sep 17 00:00:00 2001
From: Michael Hennerich <michael.hennerich@analog.com>
Date: Fri, 15 Oct 2010 09:48:10 -0700
Subject: [PATCH] Input: ad7877 - implement specified chip select behavior
According to the AD7877 datasheet:
Each transfer operation is 16-bit. If multiple read/write operations are
to be performed, CS must be taken high after the end of each read/write
operation before another read/write operation can be performed by
taking CS low again.
Make sure CS toggles after each transfer in the message.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
drivers/input/touchscreen/ad7877.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c
index 5f0221cffef9..53f4d79ee530 100644
--- a/drivers/input/touchscreen/ad7877.c
+++ b/drivers/input/touchscreen/ad7877.c
@@ -230,6 +230,7 @@ static int ad7877_read(struct spi_device *spi, u16 reg)
AD7877_READADD(reg));
req->xfer[0].tx_buf = &req->command;
req->xfer[0].len = 2;
+ req->xfer[0].cs_change = 1;
req->xfer[1].rx_buf = &req->sample;
req->xfer[1].len = 2;
@@ -295,20 +296,25 @@ static int ad7877_read_adc(struct spi_device *spi, unsigned command)
req->xfer[0].tx_buf = &req->reset;
req->xfer[0].len = 2;
+ req->xfer[0].cs_change = 1;
req->xfer[1].tx_buf = &req->ref_on;
req->xfer[1].len = 2;
req->xfer[1].delay_usecs = ts->vref_delay_usecs;
+ req->xfer[1].cs_change = 1;
req->xfer[2].tx_buf = &req->command;
req->xfer[2].len = 2;
req->xfer[2].delay_usecs = ts->vref_delay_usecs;
+ req->xfer[2].cs_change = 1;
req->xfer[3].rx_buf = &req->sample;
req->xfer[3].len = 2;
+ req->xfer[3].cs_change = 1;
req->xfer[4].tx_buf = &ts->cmd_crtl2; /*REF OFF*/
req->xfer[4].len = 2;
+ req->xfer[4].cs_change = 1;
req->xfer[5].tx_buf = &ts->cmd_crtl1; /*DEFAULT*/
req->xfer[5].len = 2;
@@ -640,17 +646,21 @@ static void ad7877_setup_ts_def_msg(struct spi_device *spi, struct ad7877 *ts)
ts->xfer[0].tx_buf = &ts->cmd_crtl1;
ts->xfer[0].len = 2;
+ ts->xfer[0].cs_change = 1;
spi_message_add_tail(&ts->xfer[0], m);
ts->xfer[1].tx_buf = &ts->cmd_dummy; /* Send ZERO */
ts->xfer[1].len = 2;
+ ts->xfer[1].cs_change = 1;
spi_message_add_tail(&ts->xfer[1], m);
- for (i = 0; i < 11; i++) {
+ for (i = 0; i < AD7877_NR_SENSE; i++) {
ts->xfer[i + 2].rx_buf = &ts->conversion_data[AD7877_SEQ_YPOS + i];
ts->xfer[i + 2].len = 2;
+ if (i < (AD7877_NR_SENSE - 1))
+ ts->xfer[i + 2].cs_change = 1;
spi_message_add_tail(&ts->xfer[i + 2], m);
}
}
--
2.20.1