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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>
This commit is contained in:
Michael Hennerich 2010-10-15 09:48:10 -07:00 committed by Dmitry Torokhov
parent 790d5c8dac
commit e92c27fb53
1 changed files with 11 additions and 1 deletions
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12
drivers/input/touchscreen/ad7877.c
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@ -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);
}
}