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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>
hifive-unleashed-5.1
Mark A. Greer 2014-09-02 15:12:24 -07:00 committed by Samuel Ortiz
parent a08e54549e
commit 4e64eff837
1 changed files with 13 additions and 1 deletions
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14
drivers/nfc/trf7970a.c
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@ -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 @@ struct trf7970a {
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 @@ static int trf7970a_config_rf_tech(struct trf7970a *trf, int tech)
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 @@ static int trf7970a_config_framing(struct trf7970a *trf, int framing)
trf->chip_status_ctrl |= TRF7970A_CHIP_STATUS_RF_ON;
usleep_range(5000, 6000);
usleep_range(trf->guard_time, trf->guard_time + 1000);
}
return 0;