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Commit 4e64eff8 authored by Mark A. Greer's avatar Mark A. Greer Committed by Samuel Ortiz
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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: default avatarMark A. Greer <mgreer@animalcreek.com>
Signed-off-by: default avatarSamuel Ortiz <sameo@linux.intel.com>
parent a08e5454

drivers/nfc/trf7970a.c

+13 −1
Original line number Diff line number Diff line
@@ -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;