On Sun, Apr 12, 2020 at 02:28:31PM -0500, Sanjay R Mehta wrote:
> +++ b/drivers/spi/spi-amd.c
> @@ -0,0 +1,341 @@
> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> +/*
> + * AMD SPI controller driver
> + *
Please make the entire comment a C++ one so things look more
intentional.
> +#define DRIVER_NAME "amd_spi"
This is unused.
> +/* M_CMD OP codes for SPI */
> +#define SPI_XFER_TX 1
> +#define SPI_XFER_RX 2
These constants should be namespaced, they're likely to collide with
generic additions.
> +static void amd_spi_execute_opcode(struct spi_master *master)
> +{
> + struct amd_spi *amd_spi = spi_master_get_devdata(master);
> + bool spi_busy;
> +
> + /* Set ExecuteOpCode bit in the CTRL0 register */
> + amd_spi_setclear_reg32(master, AMD_SPI_CTRL0_REG, AMD_SPI_EXEC_CMD,
> + AMD_SPI_EXEC_CMD);
> +
> + /* poll for SPI bus to become idle */
> + spi_busy = (ioread32((u8 __iomem *)amd_spi->io_remap_addr +
> + AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) == AMD_SPI_BUSY;
> + while (spi_busy) {
> + set_current_state(TASK_INTERRUPTIBLE);
> + schedule();
> + set_current_state(TASK_RUNNING);
> + spi_busy = (ioread32((u8 __iomem *)amd_spi->io_remap_addr +
> + AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) == AMD_SPI_BUSY;
> + }
This is a weird way to busy wait - usually you'd use a cpu_relax()
rather than a schedule(). There's also no timeout here so we could busy
wait for ever if something goes wrong.
> +static int amd_spi_master_setup(struct spi_device *spi)
> +{
> + struct spi_master *master = spi->master;
> + struct amd_spi *amd_spi = spi_master_get_devdata(master);
> +
> + amd_spi->chip_select = spi->chip_select;
> + amd_spi_select_chip(master);
This looks like it will potentially affect devices other than the
current one. setup() may be called while other devices are active it
shouldn't do that.
> + } else if (m_cmd & SPI_XFER_RX) {
> + /* Store no. of bytes to be received from
> + * FIFO
> + */
> + rx_len = xfer->len;
> + buffer = (u8 *)xfer->rx_buf;
> + /* Read data from FIFO to receive buffer */
> + for (i = 0; i < rx_len; i++)
> + buffer[i] = ioread8((u8 __iomem *)amd_spi->io_remap_addr
> + + AMD_SPI_FIFO_BASE
> + + tx_len + i);
This will only work for messages with a single receive transfer, if
there are multiple transfers then you'll need to store multiple buffers
and their lengths.
> +static int amd_spi_master_transfer(struct spi_master *master,
> + struct spi_message *msg)
> +{
> + struct amd_spi *amd_spi = spi_master_get_devdata(master);
> +
> + /*
> + * Extract spi_transfers from the spi message and
> + * program the controller.
> + */
> + amd_spi_fifo_xfer(amd_spi, msg);
> +
> + return 0;
> +}
This function is completely redundant, just inline amd_spi_fifo_xfer().
It also ignores all errors which isn't great.
> + /* Initialize the spi_master fields */
> + master->bus_num = 0;
> + master->num_chipselect = 4;
> + master->mode_bits = 0;
> + master->flags = 0;
This device is single duplex so should flag that.
> + err = spi_register_master(master);
> + if (err) {
> + dev_err(dev, "error registering SPI controller\n");
> + goto err_iounmap;
It's best to print the error code to help people debug things.
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