Re: [PATCH 1/4] NFC: trf7970a: Add support for gpio as SS

[Julian Calaby <julian.calaby@gmail.com>]

Hi Geoff,

On Tue, Apr 19, 2016 at 5:48 AM, Geoff Lansberry <geoff@kuvee.com> wrote:
> Signed-off-by: Geoff Lansberry <geoff@kuvee.com>

Can't you just use the cs-gpios property? This should require no driver changes.

This is described here:

https://www.kernel.org/doc/Documentation/devicetree/bindings/spi/spi-bus.txt

Thanks,

Julian Calaby


> ---
>  .../devicetree/bindings/net/nfc/trf7970a.txt       |  2 ++
>  drivers/nfc/trf7970a.c                             | 33 ++++++++++++++++++++--
>  2 files changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
> index 32b35a0..09c5056 100644
> --- a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
> +++ b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
> @@ -7,6 +7,7 @@ Required properties:
>  - interrupts: A single interrupt specifier.
>  - ti,enable-gpios: Two GPIO entries used for 'EN' and 'EN2' pins on the
>    TRF7970A.
> +- ti,ss-gpio: GPIO entry used for active low SS (spi slave select) on the TRF7970A
>  - vin-supply: Regulator for supply voltage to VIN pin
>
>  Optional SoC Specific Properties:
> @@ -37,6 +38,7 @@ Example (for ARM-based BeagleBone with TRF7970A on SPI1):
>                 interrupts = <14 0>;
>                 ti,enable-gpios = <&gpio2 2 GPIO_ACTIVE_LOW>,
>                                   <&gpio2 5 GPIO_ACTIVE_LOW>;
> +               ti,ss-gpio = <&gpio2 4 GPIO_ACTIVE_HIGH>;
>                 vin-supply = <&ldo3_reg>;
>                 vin-voltage-override = <5000000>;
>                 autosuspend-delay = <30000>;
> diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
> index 10842b7..2c3530a 100644
> --- a/drivers/nfc/trf7970a.c
> +++ b/drivers/nfc/trf7970a.c
> @@ -450,6 +450,7 @@ struct trf7970a {
>         bool                            adjust_resp_len;
>         int                             en2_gpio;
>         int                             en_gpio;
> +       int                             ss_gpio;
>         struct mutex                    lock;
>         unsigned int                    timeout;
>         bool                            ignore_timeout;
> @@ -462,9 +463,11 @@ static int trf7970a_cmd(struct trf7970a *trf, u8 opcode)
>         u8 cmd = TRF7970A_CMD_BIT_CTRL | TRF7970A_CMD_BIT_OPCODE(opcode);
>         int ret;
>
> +       gpio_set_value(trf->ss_gpio, 0);
>         dev_dbg(trf->dev, "cmd: 0x%x\n", cmd);
>
>         ret = spi_write(trf->spi, &cmd, 1);
> +       gpio_set_value(trf->ss_gpio, 1);
>         if (ret)
>                 dev_err(trf->dev, "%s - cmd: 0x%x, ret: %d\n", __func__, cmd,
>                                 ret);
> @@ -476,7 +479,9 @@ static int trf7970a_read(struct trf7970a *trf, u8 reg, u8 *val)
>         u8 addr = TRF7970A_CMD_BIT_RW | reg;
>         int ret;
>
> +       gpio_set_value(trf->ss_gpio, 0);
>         ret = spi_write_then_read(trf->spi, &addr, 1, val, 1);
> +       gpio_set_value(trf->ss_gpio, 1);
>         if (ret)
>                 dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
>                                 ret);
> @@ -493,6 +498,7 @@ static int trf7970a_read_cont(struct trf7970a *trf, u8 reg, u8 *buf, size_t len)
>         struct spi_message m;
>         int ret;
>
> +       gpio_set_value(trf->ss_gpio, 0);
>         dev_dbg(trf->dev, "read_cont(0x%x, %zd)\n", addr, len);
>
>         spi_message_init(&m);
> @@ -508,6 +514,7 @@ static int trf7970a_read_cont(struct trf7970a *trf, u8 reg, u8 *buf, size_t len)
>         spi_message_add_tail(&t[1], &m);
>
>         ret = spi_sync(trf->spi, &m);
> +       gpio_set_value(trf->ss_gpio, 1);
>         if (ret)
>                 dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
>                                 ret);
> @@ -519,9 +526,11 @@ static int trf7970a_write(struct trf7970a *trf, u8 reg, u8 val)
>         u8 buf[2] = { reg, val };
>         int ret;
>
> +       gpio_set_value(trf->ss_gpio, 0);
>         dev_dbg(trf->dev, "write(0x%x): 0x%x\n", reg, val);
>
>         ret = spi_write(trf->spi, buf, 2);
> +       gpio_set_value(trf->ss_gpio, 1);
>         if (ret)
>                 dev_err(trf->dev, "%s - write: 0x%x 0x%x, ret: %d\n", __func__,
>                                 buf[0], buf[1], ret);
> @@ -535,6 +544,7 @@ static int trf7970a_read_irqstatus(struct trf7970a *trf, u8 *status)
>         u8 buf[2];
>         u8 addr;
>
> +       gpio_set_value(trf->ss_gpio, 0);
>         addr = TRF7970A_IRQ_STATUS | TRF7970A_CMD_BIT_RW;
>
>         if (trf->quirks & TRF7970A_QUIRK_IRQ_STATUS_READ) {
> @@ -544,6 +554,7 @@ static int trf7970a_read_irqstatus(struct trf7970a *trf, u8 *status)
>                 ret = spi_write_then_read(trf->spi, &addr, 1, buf, 1);
>         }
>
> +       gpio_set_value(trf->ss_gpio, 1);
>         if (ret)
>                 dev_err(trf->dev, "%s - irqstatus: Status read failed: %d\n",
>                                 __func__, ret);
> @@ -559,6 +570,7 @@ static int trf7970a_read_target_proto(struct trf7970a *trf, u8 *target_proto)
>         u8 buf[2];
>         u8 addr;
>
> +       gpio_set_value(trf->ss_gpio, 0);
>         addr = TRF79070A_NFC_TARGET_PROTOCOL | TRF7970A_CMD_BIT_RW |
>                 TRF7970A_CMD_BIT_CONTINUOUS;
>
> @@ -569,6 +581,7 @@ static int trf7970a_read_target_proto(struct trf7970a *trf, u8 *target_proto)
>         else
>                 *target_proto = buf[0];
>
> +       gpio_set_value(trf->ss_gpio, 1);
>         return ret;
>  }
>
> @@ -663,6 +676,7 @@ static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
>         print_hex_dump_debug("trf7970a tx data: ", DUMP_PREFIX_NONE,
>                         16, 1, skb->data, len, false);
>
> +       gpio_set_value(trf->ss_gpio, 0);
>         spi_message_init(&m);
>
>         memset(&t, 0, sizeof(t));
> @@ -679,7 +693,7 @@ static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
>         if (ret) {
>                 dev_err(trf->dev, "%s - Can't send tx data: %d\n", __func__,
>                                 ret);
> -               return ret;
> +               goto out_err;
>         }
>
>         skb_pull(skb, len);
> @@ -706,7 +720,9 @@ static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
>
>         schedule_delayed_work(&trf->timeout_work, msecs_to_jiffies(timeout));
>
> -       return 0;
> +out_err:
> +       gpio_set_value(trf->ss_gpio, 1);
> +       return ret;
>  }
>
>  static void trf7970a_fill_fifo(struct trf7970a *trf)
> @@ -2039,6 +2055,19 @@ static int trf7970a_probe(struct spi_device *spi)
>                 return ret;
>         }
>
> +       trf->ss_gpio = of_get_named_gpio(np, "ti,ss-gpio", 0);
> +       if (!gpio_is_valid(trf->ss_gpio)) {
> +               dev_err(trf->dev, "No SS GPIO property\n");
> +               return trf->ss_gpio;
> +       }
> +
> +       ret = devm_gpio_request_one(trf->dev, trf->ss_gpio,
> +                       GPIOF_DIR_OUT | GPIOF_INIT_HIGH, "trf7970a SS");
> +       if (ret) {
> +               dev_err(trf->dev, "Can't request SS GPIO: %d\n", ret);
> +               return ret;
> +       }
> +
>         if (of_property_read_bool(np, "en2-rf-quirk"))
>                 trf->quirks |= TRF7970A_QUIRK_EN2_MUST_STAY_LOW;
>
> --
> 1.9.1
>
> --
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-- 
Julian Calaby

Email: julian.calaby@gmail.com
Profile: http://www.google.com/profiles/julian.calaby/