Re: [PATCH v8 3/3] fpga: Add support for Lattice iCE40 FPGAs

Marek Vasut
2016-11-07T18:01:12Z

On 11/07/2016 03:49 AM, Joel Holdsworth wrote:
> The Lattice iCE40 is a family of FPGAs with a minimalistic architecture
> and very regular structure, designed for low-cost, high-volume consumer
> and system applications.

[...]

> +static int ice40_fpga_ops_write_init(struct fpga_manager *mgr, u32 flags,
> + const char *buf, size_t count)
> +{
> + struct ice40_fpga_priv *priv = mgr->priv;
> + struct spi_device *dev = priv->dev;
> + struct spi_message message;
> + struct spi_transfer assert_cs_then_reset_delay = {.cs_change = 1,
> + .delay_usecs = ICE40_SPI_FPGAMGR_RESET_DELAY};

Should be this way for the sake of readability, fix globally:

struct spi_transfer assert_cs_then_reset_delay = {
.cs_change = 1,
.delay_usecs = ICE40_SPI_FPGAMGR_RESET_DELAY
};

Also I believe this could be const.

> + struct spi_transfer housekeeping_delay_then_release_cs = {
> + .delay_usecs = ICE40_SPI_FPGAMGR_HOUSEKEEPING_DELAY};

Don't we have some less hacky way of toggling the nCS ? Is this even nCS
or is this some control pin of the FPGA ? Maybe it should be treated
like a regular GPIO instead ?

[...]

> +static int ice40_fpga_ops_write_complete(struct fpga_manager *mgr, u32 flags)
> +{
> + struct ice40_fpga_priv *priv = mgr->priv;
> + struct spi_device *dev = priv->dev;
> + const u8 padding[ICE40_SPI_FPGAMGR_NUM_ACTIVATION_BYTES] = {0,};

The comma is not needed.

> +
> + /* Check CDONE is asserted */
> + if (!gpiod_get_value(priv->cdone)) {
> + dev_err(&dev->dev,
> + "CDONE was not asserted after firmware transfer\n");
> + return -EIO;
> + }
> +
> + /* Send of zero-padding to activate the firmware */
> + return spi_write(dev, padding, sizeof(padding));
> +}

[...]

> + /* Check board setup data. */
> + if (spi->max_speed_hz > 25000000) {
> + dev_err(dev, "Speed is too high\n");
> + return -EINVAL;
> + }
> +
> + if (spi->max_speed_hz < 1000000) {
> + dev_err(dev, "Speed is too low\n");
> + return -EINVAL;
> + }

Do you have some explanation for this limitation ?

[...]

--
Best regards,
Marek Vasut
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