* Re: [PATCH v2 2/2] fpga manager: xilinx-spi: check INIT_B pin during write_init
[not found] ` <20200622133723.23326-2-luca@lucaceresoli.net>
@ 2020-06-26 21:02 ` Moritz Fischer
0 siblings, 0 replies; 2+ messages in thread
From: Moritz Fischer @ 2020-06-26 21:02 UTC (permalink / raw)
To: Luca Ceresoli
Cc: devicetree, linux-fpga, Michal Simek, linux-kernel, Rob Herring,
Moritz Fischer, Anatolij Gustschin, linux-arm-kernel
On Mon, Jun 22, 2020 at 03:37:23PM +0200, Luca Ceresoli wrote:
> The INIT_B pin reports the status during startup and after the end of the
> programming process. However the current driver completely ignores it.
>
> Check the pin status during startup to make sure programming is never
> started too early and also to detect any hardware issues in the FPGA
> connection.
>
> This is optional for backward compatibility. If INIT_B is not passed by
> device tree, just fallback to the old udelays.
>
> Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
>
> ---
>
> Changes in v2:
> - rename DT property init_b-gpios to init-b-gpios (Rob Herring suggested to
> not use '_' in property names)
> - improve wait_for_init_b() documentation and variable naming
> ---
> drivers/fpga/xilinx-spi.c | 55 ++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
> index 799ae04301be..2967aa2a74e2 100644
> --- a/drivers/fpga/xilinx-spi.c
> +++ b/drivers/fpga/xilinx-spi.c
> @@ -23,6 +23,7 @@
> struct xilinx_spi_conf {
> struct spi_device *spi;
> struct gpio_desc *prog_b;
> + struct gpio_desc *init_b;
> struct gpio_desc *done;
> };
>
> @@ -36,11 +37,45 @@ static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
> return FPGA_MGR_STATE_UNKNOWN;
> }
>
> +/**
> + * wait_for_init_b - wait for the INIT_B pin to have a given state, or wait
> + * a given delay if the pin is unavailable
> + *
> + * @mgr: The FPGA manager object
> + * @value: Value INIT_B to wait for (1 = asserted = low)
> + * @alt_udelay: Delay to wait if the INIT_B GPIO is not available
> + *
> + * Returns 0 when the INIT_B GPIO reached the given state or -ETIMEDOUT if
> + * too much time passed waiting for that. If no INIT_B GPIO is available
> + * then always return 0.
> + */
> +static int wait_for_init_b(struct fpga_manager *mgr, int value,
> + unsigned long alt_udelay)
> +{
> + struct xilinx_spi_conf *conf = mgr->priv;
> + unsigned long timeout = jiffies + msecs_to_jiffies(1000);
> +
> + if (conf->init_b) {
> + while (time_before(jiffies, timeout)) {
> + /* dump_state(conf, "wait for init_d .."); */
> + if (gpiod_get_value(conf->init_b) == value)
> + return 0;
> + usleep_range(100, 400);
> + }
> + return -ETIMEDOUT;
> + }
> +
> + udelay(alt_udelay);
> +
> + return 0;
> +}
> +
> static int xilinx_spi_write_init(struct fpga_manager *mgr,
> struct fpga_image_info *info,
> const char *buf, size_t count)
> {
> struct xilinx_spi_conf *conf = mgr->priv;
> + int err;
>
> if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
> dev_err(&mgr->dev, "Partial reconfiguration not supported.\n");
> @@ -49,10 +84,21 @@ static int xilinx_spi_write_init(struct fpga_manager *mgr,
>
> gpiod_set_value(conf->prog_b, 1);
>
> - udelay(1); /* min is 500 ns */
> + err = wait_for_init_b(mgr, 1, 1); /* min is 500 ns */
> + if (err) {
> + dev_err(&mgr->dev, "INIT_B pin did not go low\n");
> + gpiod_set_value(conf->prog_b, 0);
> + return err;
> + }
>
> gpiod_set_value(conf->prog_b, 0);
>
> + err = wait_for_init_b(mgr, 0, 0);
> + if (err) {
> + dev_err(&mgr->dev, "INIT_B pin did not go high\n");
> + return err;
> + }
> +
> if (gpiod_get_value(conf->done)) {
> dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
> return -EIO;
> @@ -154,6 +200,13 @@ static int xilinx_spi_probe(struct spi_device *spi)
> return PTR_ERR(conf->prog_b);
> }
>
> + conf->init_b = devm_gpiod_get_optional(&spi->dev, "init-b", GPIOD_IN);
> + if (IS_ERR(conf->init_b)) {
> + dev_err(&spi->dev, "Failed to get INIT_B gpio: %ld\n",
> + PTR_ERR(conf->init_b));
> + return PTR_ERR(conf->init_b);
> + }
> +
> conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
> if (IS_ERR(conf->done)) {
> dev_err(&spi->dev, "Failed to get DONE gpio: %ld\n",
> --
> 2.27.0
>
Will apply to for-next,
Thanks!
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