linux-kernel - Re: [PATCH 2/2] spi: microchip-core-qspi: Add support for microchip fpga qspi controllers

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Message-ID: <CAH_iE_1Khx=qAKWwWcL56fLQeutP-DvYvC4VMd_zzzxKkMrJLQ@mail.gmail.com>
Date:   Mon, 1 Aug 2022 16:39:09 +0530
From:   naga sureshkumar <nagasuresh12@...il.com>
To:     Conor.Dooley@...rochip.com
Cc:     Nagasuresh.Relli@...rochip.com, broonie@...nel.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] spi: microchip-core-qspi: Add support for microchip
 fpga qspi controllers

Hi Conor,

On Mon, Aug 1, 2022 at 4:19 PM <Conor.Dooley@...rochip.com> wrote:
>
> On 01/08/2022 10:42, Naga Sureshkumar Relli wrote:
> > Add a driver for Microchip FPGA QSPI controllers. This driver also
> > supports "hard" QSPI controllers on Polarfire SoC.
> >
> > Signed-off-by: Naga Sureshkumar Relli <nagasuresh.relli@...rochip.com>
> > ---
>
> ---8<---
>
> > +static int mchp_coreqspi_probe(struct platform_device *pdev)
> > +{
> > +     struct spi_controller *ctlr;
> > +     struct mchp_coreqspi *qspi;
> > +     struct device *dev = &pdev->dev;
> > +     struct device_node *np = dev->of_node;
> > +     int ret;
> > +
> > +     ctlr = spi_alloc_master(&pdev->dev, sizeof(*qspi));
> > +     if (!ctlr)
> > +             return -ENOMEM;
>
> Argh... I am sorry for not mentioning this when you asked me if
> I thought the driver was ready to be sent upstream, but I think
> we should try to use the devm_ versions of these functions.
Ok.
>
> > +
> > +     qspi = spi_controller_get_devdata(ctlr);
>
> Is there a reason to use spi_controller_get_devdata() rather than
> spi_master_get_devdata() ?
Both are the same.
https://github.com/torvalds/linux/blob/master/include/linux/spi/spi.h#L1497
Ref: https://github.com/torvalds/linux/commit/8caab75fd2c2a92667cbb1cd315720bede3feaa9
>
> > +     platform_set_drvdata(pdev, qspi);
> > +
> > +     qspi->regs = devm_platform_ioremap_resource(pdev, 0);
> > +     if (IS_ERR(qspi->regs)) {
> > +             ret = PTR_ERR(qspi->regs);
> > +             goto remove_master;
>
> Using devm_spi_alloc_master() above would simplify this
> to just a return of dev_err_probe() & ditto for every
> time we do a "goto remove_master"
Ok. I will update to use devm_ versions.
>
> > +     }
> > +
> > +     qspi->clk = devm_clk_get(&pdev->dev, NULL);
> > +     if (IS_ERR(qspi->clk)) {
> > +             dev_err(&pdev->dev, "clock not found.\n");
> > +             ret = PTR_ERR(qspi->clk);
> > +             goto remove_master;
> > +     }
> > +
> > +     ret = clk_prepare_enable(qspi->clk);
> > +     if (ret) {
> > +             dev_err(&pdev->dev, "failed to enable clock\n");
> > +             goto remove_master;
> > +     }
> > +
> > +     init_completion(&qspi->data_completion);
> > +     mutex_init(&qspi->op_lock);
> > +
> > +     qspi->irq = platform_get_irq(pdev, 0);
> > +     if (qspi->irq <= 0) {
> > +             ret = qspi->irq;
> > +             goto clk_dis_all;
> > +     }
> > +
> > +     ret = devm_request_irq(&pdev->dev, qspi->irq, mchp_coreqspi_isr,
> > +                            0, pdev->name, qspi);
> > +     if (ret != 0) {
> > +             dev_err(&pdev->dev, "request_irq failed %d\n", ret);
> > +             goto clk_dis_all;
> > +     }
> > +
> > +     ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
> > +     ctlr->mem_ops = &mchp_coreqspi_mem_ops;
> > +     ctlr->setup = mchp_coreqspi_setup_op;
> > +     ctlr->mode_bits = SPI_CPOL | SPI_CPHA | SPI_RX_DUAL | SPI_RX_QUAD |
> > +                       SPI_TX_DUAL | SPI_TX_QUAD;
> > +     ctlr->dev.of_node = np;
> > +
> > +     ret = devm_spi_register_controller(&pdev->dev, ctlr);
> > +     if (ret) {
> > +             dev_err(&pdev->dev, "spi_register_controller failed\n");
> > +             goto clk_dis_all;
> > +     }
> > +
> > +     return 0;
> > +
> > +clk_dis_all:
> > +     clk_disable_unprepare(qspi->clk);
>
> If we move the clk prepare & enable later in probe, ie after
> getting the irq, this goto could be removed too because the
> only place requiring teardown of the clock would be the error
> path of devm_spi_register_controller().
ok.
>
> > +remove_master:
> > +     spi_controller_put(ctlr);
>
> With devm_spi_alloc_master() this put is no longer needed &
> we can return a nice dev_err_probe() for each error :)
ok. I will send the next version with these updates.
>
> > +
> > +     return ret;
> > +}
>
> Thanks Suresh.
> Conor.