[PATCH 2/3] NFC: trf7970a: Add device tree option of 1.8 Volt IO voltage

[Geoff Lansberry]

From: Geoff Lansberry <ge...@kuvee.com>

---
 Documentation/devicetree/bindings/net/nfc/trf7970a.txt |  2 ++
 drivers/nfc/trf7970a.c                                 | 13 ++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt 
b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
index 9dda879..208f045 100644
--- a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
+++ b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
@@ -21,6 +21,7 @@ Optional SoC Specific Properties:
 - t5t-rmb-extra-byte-quirk: Specify that the trf7970a has the erratum
   where an extra byte is returned by Read Multiple Block commands issued
   to Type 5 tags.
+- vdd_io_1v8: Set to specify that the trf7970a io voltage should be set to 1.8V
 - crystal_27mhz: Set to specify that the input frequency to the trf7970a is 
27.12MHz
 
 
@@ -45,6 +46,7 @@ Example (for ARM-based BeagleBone with TRF7970A on SPI1):
                irq-status-read-quirk;
                en2-rf-quirk;
                t5t-rmb-extra-byte-quirk;
+               vdd_io_1v8;
                crystal_27mhz;
                status = "okay";
        };
diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
index 2d2a077..b4c37ab 100644
--- a/drivers/nfc/trf7970a.c
+++ b/drivers/nfc/trf7970a.c
@@ -441,6 +441,7 @@ struct trf7970a {
        u8                              iso_ctrl_tech;
        u8                              modulator_sys_clk_ctrl;
        u8                              special_fcn_reg1;
+       u8                              io_ctrl;
        unsigned int                    guard_time;
        int                             technology;
        int                             framing;
@@ -1048,6 +1049,11 @@ static int trf7970a_init(struct trf7970a *trf)
        if (ret)
                goto err_out;
 
+       ret = trf7970a_write(trf, TRF7970A_REG_IO_CTRL,
+                       trf->io_ctrl|TRF7970A_REG_IO_CTRL_VRS(0x1));
+       if (ret)
+               goto err_out;
+
        ret = trf7970a_write(trf, TRF7970A_NFC_TARGET_LEVEL, 0);
        if (ret)
                goto err_out;
@@ -1764,7 +1770,7 @@ static int _trf7970a_tg_listen(struct nfc_digital_dev 
*ddev, u16 timeout,
                goto out_err;
 
        ret = trf7970a_write(trf, TRF7970A_REG_IO_CTRL,
-                       TRF7970A_REG_IO_CTRL_VRS(0x1));
+                       trf->io_ctrl|TRF7970A_REG_IO_CTRL_VRS(0x1));
        if (ret)
                goto out_err;
 
@@ -2058,6 +2064,11 @@ static int trf7970a_probe(struct spi_device *spi)
                return ret;
        }
 
+       if (of_property_read_bool(np, "vdd_io_1v8")) {
+               trf->io_ctrl = TRF7970A_REG_IO_CTRL_IO_LOW;
+               dev_dbg(trf->dev, "trf7970a config vdd_io_1v8\n");
+       }
+
        if (of_property_read_bool(np, "crystal_27mhz")) {
                trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_27MHZ;
                dev_dbg(trf->dev, "trf7970a configure crystal_27mhz\n");
-- 
Signed-off-by: Geoff Lansberry <ge...@kuvee.com>