NFC: trf7970a: Don't turn on RF if there is already an RF field
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>
diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
index ab6e276..0f09278 100644
--- a/drivers/nfc/trf7970a.c
+++ b/drivers/nfc/trf7970a.c
@@ -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 @@
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 @@
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)