Date:   Mon, 08 Oct 2018 16:43:17 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Alok Chauhan <alokc@...eaurora.org>, broonie@...nel.org,
        dianders@...omium.org, linux-kernel@...r.kernel.org,
        linux-spi@...r.kernel.org, mka@...omium.org
Cc:     linux-arm-msm@...r.kernel.org,
        Girish Mahadevan <girishm@...eaurora.org>,
        Dilip Kota <dkota@...eaurora.org>,
        Alok Chauhan <alokc@...eaurora.org>
Subject: Re: [PATCH V5 3/3] spi: spi-geni-qcom: Add SPI driver support for GENI based
 QUP

Quoting Alok Chauhan (2018-10-03 06:44:25)
>

I just have a handful of nitpicks which can be fixed later in
follow-ups. Otherwise:

Reviewed-by: Stephen Boyd <swboyd@...omium.org>

> diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
> new file mode 100644
> index 0000000..6432ecc
> --- /dev/null
> +++ b/drivers/spi/spi-geni-qcom.c
> @@ -0,0 +1,703 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
> +
[...]
> +#define SPI_TX_ONLY            1
> +#define SPI_RX_ONLY            2
> +#define SPI_FULL_DUPLEX                3
> +#define SPI_TX_RX              7
> +#define SPI_CS_ASSERT          8
> +#define SPI_CS_DEASSERT                9
> +#define SPI_SCK_ONLY           10
> +/* M_CMD params for SPI */
> +#define SPI_PRE_CMD_DELAY      BIT(0)
> +#define TIMESTAMP_BEFORE       BIT(1)
> +#define FRAGMENTATION          BIT(2)
> +#define TIMESTAMP_AFTER                BIT(3)
> +#define POST_CMD_DELAY         BIT(4)
> +
> +/* SPI M_COMMAND OPCODE */
> +enum spi_mcmd_code {

Nitpick: rename spi_m_cmd_opcode and drop the comment?

> +       CMD_NONE,
> +       CMD_XFER,
> +       CMD_CS,
> +       CMD_CANCEL,
> +};
> +
> +

Nitpick: Drop double newline.

> +struct spi_geni_master {
> +       struct geni_se se;
> +       struct device *dev;
> +       u32 tx_fifo_depth;
> +       u32 fifo_width_bits;
> +       u32 tx_wm;
> +       unsigned long cur_speed_hz;
> +       unsigned int cur_bits_per_word;
> +       unsigned int tx_rem_bytes;
> +       unsigned int rx_rem_bytes;
> +       const struct spi_transfer *cur_xfer;
> +       struct completion xfer_done;
> +       unsigned int oversampling;
> +       spinlock_t lock;
> +       unsigned int cur_mcmd;

Niptick: Use the enum?

> +       int irq;
> +};
> +
> +static void handle_fifo_timeout(struct spi_master *spi,
> +                               struct spi_message *msg);
> +
> +static int get_spi_clk_cfg(unsigned int speed_hz,
> +                       struct spi_geni_master *mas,
> +                       unsigned int *clk_idx,
> +                       unsigned int *clk_div)
> +{
> +       unsigned long sclk_freq;
> +       unsigned int actual_hz;
> +       struct geni_se *se = &mas->se;
> +       int ret;
> +
> +       ret = geni_se_clk_freq_match(&mas->se,
> +                               speed_hz * mas->oversampling,
> +                               clk_idx, &sclk_freq, false);
> +       if (ret) {
> +               dev_err(mas->dev, "Failed(%d) to find src clk for %dHz\n",
> +                                                       ret, speed_hz);
> +               return ret;
> +       }
> +
> +       *clk_div = DIV_ROUND_UP(sclk_freq, mas->oversampling * speed_hz);
> +       actual_hz = sclk_freq / (mas->oversampling * *clk_div);
> +
> +       dev_dbg(mas->dev, "req %u=>%u sclk %lu, idx %d, div %d\n", speed_hz,
> +                               actual_hz, sclk_freq, *clk_idx, *clk_div);
> +       ret = clk_set_rate(se->clk, sclk_freq);
> +       if (ret)
> +               dev_err(mas->dev, "clk_set_rate failed %d\n", ret);
> +       return ret;
> +}
> +
> +static void spi_geni_set_cs(struct spi_device *slv, bool set_flag)
> +{
> +       struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
> +       struct spi_master *spi = dev_get_drvdata(mas->dev);
> +       struct geni_se *se = &mas->se;
> +       unsigned long timeout;
> +
> +       reinit_completion(&mas->xfer_done);
> +       pm_runtime_get_sync(mas->dev);
> +       if (!(slv->mode & SPI_CS_HIGH))
> +               set_flag = !set_flag;
> +
> +       mas->cur_mcmd = CMD_CS;
> +       if (set_flag)
> +               geni_se_setup_m_cmd(se, SPI_CS_ASSERT, 0);
> +       else
> +               geni_se_setup_m_cmd(se, SPI_CS_DEASSERT, 0);
> +
> +       timeout = wait_for_completion_timeout(&mas->xfer_done, HZ);

Nitpick: s/timeout/time_left/

> +       if (!timeout)
> +               handle_fifo_timeout(spi, NULL);
> +
> +       pm_runtime_put(mas->dev);
> +}
> +
[...]
> +
> +static irqreturn_t geni_spi_isr(int irq, void *data)
> +{
> +       struct spi_master *spi = data;
> +       struct spi_geni_master *mas = spi_master_get_devdata(spi);
> +       struct geni_se *se = &mas->se;
> +       u32 m_irq;
> +       unsigned long flags;
> +       irqreturn_t ret = IRQ_HANDLED;
> +
> +       if (mas->cur_mcmd == CMD_NONE)
> +               return IRQ_NONE;
> +
> +       spin_lock_irqsave(&mas->lock, flags);
> +       m_irq = readl(se->base + SE_GENI_M_IRQ_STATUS);
> +
> +       if ((m_irq & M_RX_FIFO_WATERMARK_EN) || (m_irq & M_RX_FIFO_LAST_EN))
> +               geni_spi_handle_rx(mas);
> +
> +       if (m_irq & M_TX_FIFO_WATERMARK_EN)
> +               geni_spi_handle_tx(mas);
> +
> +       if (m_irq & M_CMD_DONE_EN) {
> +               if (mas->cur_mcmd == CMD_XFER)
> +                       spi_finalize_current_transfer(spi);
> +               else if (mas->cur_mcmd == CMD_CS)
> +                       complete(&mas->xfer_done);
> +               mas->cur_mcmd = CMD_NONE;
> +               /*
> +                * If this happens, then a CMD_DONE came before all the Tx
> +                * buffer bytes were sent out. This is unusual, log this
> +                * condition and disable the WM interrupt to prevent the
> +                * system from stalling due an interrupt storm.
> +                * If this happens when all Rx bytes haven't been received, log
> +                * the condition.
> +                * The only known time this can happen is if bits_per_word != 8
> +                * and some registers that expect xfer lengths in num spi_words
> +                * weren't written correctly.
> +                */
> +               if (mas->tx_rem_bytes) {
> +                       writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
> +                       dev_err(mas->dev, "Premature done. tx_rem = %d bpw%d\n",
> +                               mas->tx_rem_bytes, mas->cur_bits_per_word);
> +               }
> +               if (mas->rx_rem_bytes)
> +                       dev_err(mas->dev, "Premature done. rx_rem = %d bpw%d\n",
> +                               mas->rx_rem_bytes, mas->cur_bits_per_word);
> +       }
> +
> +       if ((m_irq & M_CMD_CANCEL_EN) || (m_irq & M_CMD_ABORT_EN)) {
> +               mas->cur_mcmd = CMD_NONE;
> +               complete(&mas->xfer_done);
> +       }
> +
> +       writel(m_irq, se->base + SE_GENI_M_IRQ_CLEAR);
> +       spin_unlock_irqrestore(&mas->lock, flags);
> +       return ret;

Nitpick: Now this always returns IRQ_HANDLED, and we assign ret just to
do that. Perhaps only return IRQ_HANDLED if one of the above if
conditions is taken?

> +}
> +
> +static int spi_geni_probe(struct platform_device *pdev)
> +{
> +       int ret;
> +       struct spi_master *spi;
> +       struct spi_geni_master *mas;
> +       struct resource *res;
> +       struct geni_se *se;
> +
> +       spi = spi_alloc_master(&pdev->dev, sizeof(*mas));
> +       if (!spi)
> +               return -ENOMEM;
> +
> +       platform_set_drvdata(pdev, spi);
> +       mas = spi_master_get_devdata(spi);
> +       mas->dev = &pdev->dev;
> +       mas->se.dev = &pdev->dev;
> +       mas->se.wrapper = dev_get_drvdata(pdev->dev.parent);
> +       se = &mas->se;
> +
> +       spi->bus_num = -1;
> +       spi->dev.of_node = pdev->dev.of_node;
> +       mas->se.clk = devm_clk_get(&pdev->dev, "se");
> +       if (IS_ERR(mas->se.clk)) {
> +               ret = PTR_ERR(mas->se.clk);
> +               dev_err(&pdev->dev, "Err getting SE Core clk %d\n", ret);
> +               goto spi_geni_probe_err;
> +       }
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       se->base = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(se->base)) {
> +               ret = PTR_ERR(se->base);
> +               goto spi_geni_probe_err;
> +       }
> +
> +       spi->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_CS_HIGH;
> +       spi->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
> +       spi->num_chipselect = 4;
> +       spi->max_speed_hz = 50000000;
> +       spi->prepare_message = spi_geni_prepare_message;
> +       spi->transfer_one = spi_geni_transfer_one;
> +       spi->auto_runtime_pm = true;
> +       spi->handle_err = handle_fifo_timeout;
> +       spi->set_cs = spi_geni_set_cs;
> +
> +       init_completion(&mas->xfer_done);
> +       spin_lock_init(&mas->lock);
> +       pm_runtime_enable(&pdev->dev);
> +
> +       ret = spi_geni_init(mas);
> +       if (ret)
> +               goto spi_geni_probe_runtime_disable;
> +
> +       mas->irq = platform_get_irq(pdev, 0);
> +       if (mas->irq < 0) {
> +               ret = mas->irq;
> +               dev_err(&pdev->dev, "Err getting IRQ %d\n", ret);
> +               goto spi_geni_probe_runtime_disable;
> +       }

Nitpick: If you got the irq earlier before allocating anything then nothing has
to be put on failure path.

> +
> +       ret = request_irq(mas->irq, geni_spi_isr,
> +                       IRQF_TRIGGER_HIGH, "spi_geni", spi);
> +       if (ret)
> +               goto spi_geni_probe_runtime_disable;
> +
> +       ret = spi_register_master(spi);
> +       if (ret)
> +               goto spi_geni_probe_free_irq;
> +
> +       return 0;
> +spi_geni_probe_free_irq:
> +       free_irq(mas->irq, spi);
> +spi_geni_probe_runtime_disable:
> +       pm_runtime_disable(&pdev->dev);
> +spi_geni_probe_err:
> +       spi_master_put(spi);
> +       return ret;
> +}

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