NFC: trf7970a: Add RF technology specific guard times
When turning on the RF field, the driver must wait
an RF-technology-specific amount of time (known as
the guard time) before modulating the field.
Currently, the driver waits 5 ms but that is too
short for NFCF and too long for ISO/IEC 15693.
Fix this by determining the guard time when the
RF technology is set and delaying that amount
of time when turning on the RF field.
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 ce9686c..22485e7 100644
--- a/drivers/nfc/trf7970a.c
+++ b/drivers/nfc/trf7970a.c
@@ -134,6 +134,12 @@
#define TRF7970A_WAIT_FOR_FIFO_DRAIN_TIMEOUT 3
#define TRF7970A_WAIT_TO_ISSUE_ISO15693_EOF 20
+/* Guard times for various RF technologies (in us) */
+#define TRF7970A_GUARD_TIME_NFCA 5000
+#define TRF7970A_GUARD_TIME_NFCB 5000
+#define TRF7970A_GUARD_TIME_NFCF 20000
+#define TRF7970A_GUARD_TIME_15693 1000
+
/* Quirks */
/* Erratum: When reading IRQ Status register on trf7970a, we must issue a
* read continuous command for IRQ Status and Collision Position registers.
@@ -351,6 +357,7 @@
u8 iso_ctrl_tech;
u8 modulator_sys_clk_ctrl;
u8 special_fcn_reg1;
+ unsigned int guard_time;
int technology;
int framing;
u8 tx_cmd;
@@ -887,22 +894,27 @@
case NFC_DIGITAL_RF_TECH_106A:
trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_14443A_106;
trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_OOK;
+ trf->guard_time = TRF7970A_GUARD_TIME_NFCA;
break;
case NFC_DIGITAL_RF_TECH_106B:
trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_14443B_106;
trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_ASK10;
+ trf->guard_time = TRF7970A_GUARD_TIME_NFCB;
break;
case NFC_DIGITAL_RF_TECH_212F:
trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_FELICA_212;
trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_ASK10;
+ trf->guard_time = TRF7970A_GUARD_TIME_NFCF;
break;
case NFC_DIGITAL_RF_TECH_424F:
trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_FELICA_424;
trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_ASK10;
+ trf->guard_time = TRF7970A_GUARD_TIME_NFCF;
break;
case NFC_DIGITAL_RF_TECH_ISO15693:
trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_15693_SGL_1OF4_2648;
trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_OOK;
+ trf->guard_time = TRF7970A_GUARD_TIME_15693;
break;
default:
dev_dbg(trf->dev, "Unsupported rf technology: %d\n", tech);
@@ -971,7 +983,7 @@
trf->chip_status_ctrl |= TRF7970A_CHIP_STATUS_RF_ON;
- usleep_range(5000, 6000);
+ usleep_range(trf->guard_time, trf->guard_time + 1000);
}
return 0;