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NFC: trf7970a: Don't turn on RF if there is already an RF field

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Currently, the trf7970a driver blindly turns on its
RF field when configuring its framing.  This isn't
a good idea if there is already a device generating
an RF field.  Instead, check if there is already an
RF field present before turning on this device's RF
field and, if there is, return EBUSY.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Mark A. Greer 2014-09-02 15:12:42 -07:00 committed by Samuel Ortiz
parent 7149d6bfec
commit 851ee3cbf8
1 changed files with 49 additions and 2 deletions
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51
drivers/nfc/trf7970a.c
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@ -164,8 +164,8 @@
#define TRF7970A_CMD_CLOSE_SLOT 0x15
#define TRF7970A_CMD_BLOCK_RX 0x16
#define TRF7970A_CMD_ENABLE_RX 0x17
#define TRF7970A_CMD_TEST_EXT_RF 0x18
#define TRF7970A_CMD_TEST_INT_RF 0x19
#define TRF7970A_CMD_TEST_INT_RF 0x18
#define TRF7970A_CMD_TEST_EXT_RF 0x19
#define TRF7970A_CMD_RX_GAIN_ADJUST 0x1a
/* Bits determining whether its a direct command or register R/W,
@ -280,6 +280,10 @@
TRF7970A_IRQ_STATUS_PARITY_ERROR | \
TRF7970A_IRQ_STATUS_CRC_ERROR)
#define TRF7970A_RSSI_OSC_STATUS_RSSI_MASK (BIT(2) | BIT(1) | BIT(0))
#define TRF7970A_RSSI_OSC_STATUS_RSSI_X_MASK (BIT(5) | BIT(4) | BIT(3))
#define TRF7970A_RSSI_OSC_STATUS_RSSI_OSC_OK BIT(6)
#define TRF7970A_SPECIAL_FCN_REG1_COL_7_6 BIT(0)
#define TRF7970A_SPECIAL_FCN_REG1_14_ANTICOLL BIT(1)
#define TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX BIT(2)
@ -989,9 +993,43 @@ static int trf7970a_in_config_rf_tech(struct trf7970a *trf, int tech)
return ret;
}
static int trf7970a_is_rf_field(struct trf7970a *trf, bool *is_rf_field)
{
int ret;
u8 rssi;
ret = trf7970a_write(trf, TRF7970A_CHIP_STATUS_CTRL,
trf->chip_status_ctrl | TRF7970A_CHIP_STATUS_REC_ON);
if (ret)
return ret;
ret = trf7970a_cmd(trf, TRF7970A_CMD_TEST_EXT_RF);
if (ret)
return ret;
usleep_range(50, 60);
ret = trf7970a_read(trf, TRF7970A_RSSI_OSC_STATUS, &rssi);
if (ret)
return ret;
ret = trf7970a_write(trf, TRF7970A_CHIP_STATUS_CTRL,
trf->chip_status_ctrl);
if (ret)
return ret;
if (rssi & TRF7970A_RSSI_OSC_STATUS_RSSI_MASK)
*is_rf_field = true;
else
*is_rf_field = false;
return 0;
}
static int trf7970a_in_config_framing(struct trf7970a *trf, int framing)
{
u8 iso_ctrl = trf->iso_ctrl_tech;
bool is_rf_field = false;
int ret;
dev_dbg(trf->dev, "framing: %d\n", framing);
@ -1024,6 +1062,15 @@ static int trf7970a_in_config_framing(struct trf7970a *trf, int framing)
trf->framing = framing;
if (!(trf->chip_status_ctrl & TRF7970A_CHIP_STATUS_RF_ON)) {
ret = trf7970a_is_rf_field(trf, &is_rf_field);
if (ret)
return ret;
if (is_rf_field)
return -EBUSY;
}
if (iso_ctrl != trf->iso_ctrl) {
ret = trf7970a_write(trf, TRF7970A_ISO_CTRL, iso_ctrl);
if (ret)