linux-kernel - Re: [PATCH v3 1/1] gpio: mpfs: add polarfire soc gpio support

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Message-ID: <2d7f72d3e89686d3ba5cff5df8cfe443d04fc5f4.camel@microchip.com>
Date:   Sat, 16 Jul 2022 15:21:48 +0000
From:   <Lewis.Hanly@...rochip.com>
To:     <maz@...nel.org>
CC:     <linux-riscv@...ts.infradead.org>, <Conor.Dooley@...rochip.com>,
        <brgl@...ev.pl>, <linux-gpio@...r.kernel.org>,
        <linus.walleij@...aro.org>, <palmer@...belt.com>,
        <linux-kernel@...r.kernel.org>, <Daire.McNamara@...rochip.com>
Subject: Re: [PATCH v3 1/1] gpio: mpfs: add polarfire soc gpio support

Thanks Marc,

On Sat, 2022-07-16 at 11:33 +0100, Marc Zyngier wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
> 
> On Sat, 16 Jul 2022 08:11:13 +0100,
> <lewis.hanly@...rochip.com> wrote:
> > From: Lewis Hanly <lewis.hanly@...rochip.com>
> > 
> > Add a driver to support the Polarfire SoC gpio controller.
> > 
> > Signed-off-by: Lewis Hanly <lewis.hanly@...rochip.com>
> 
> [...]
> 
> > +static int mpfs_gpio_child_to_parent_hwirq(struct gpio_chip *gc,
> > +                                        unsigned int child,
> > +                                        unsigned int child_type,
> > +                                        unsigned int *parent,
> > +                                        unsigned int *parent_type)
> > +{
> > +     struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
> > +     struct irq_data *d = irq_get_irq_data(mpfs_gpio-
> > >irq_number[child]);
> 
> This looks totally wrong. It means that you have already instantiated
> part of the hierarchy, and it is likely that you will get multiple
> hierarchy sharing some levels, which isn't intended.

Some background why I use the above.
We need to support both direct and non-direct IRQ connections to the
PLIC. 
In direct mode the GPIO IRQ's are connected directly to the PLIC and
certainly no need for the above. GPIO's can also be configured in non-
direct, which means they use a shared IRQ, hence the above.


> 
> > +     *parent_type = IRQ_TYPE_NONE;
> > +     *parent = irqd_to_hwirq(d);
> > +
> > +     return 0;
> > +}
> > +
> > +static int mpfs_gpio_probe(struct platform_device *pdev)
> > +{
> > +     struct clk *clk;
> > +     struct device *dev = &pdev->dev;
> > +     struct device_node *node = pdev->dev.of_node;
> > +     struct device_node *irq_parent;
> > +     struct gpio_irq_chip *girq;
> > +     struct irq_domain *parent;
> > +     struct mpfs_gpio_chip *mpfs_gpio;
> > +     int i, ret, ngpio;
> > +
> > +     mpfs_gpio = devm_kzalloc(dev, sizeof(*mpfs_gpio),
> > GFP_KERNEL);
> > +     if (!mpfs_gpio)
> > +             return -ENOMEM;
> > +
> > +     mpfs_gpio->base = devm_platform_ioremap_resource(pdev, 0);
> > +     if (IS_ERR(mpfs_gpio->base))
> > +             return dev_err_probe(dev, PTR_ERR(mpfs_gpio->clk),
> > "input clock not found.\n");
> > +
> > +     clk = devm_clk_get(dev, NULL);
> > +     if (IS_ERR(clk))
> > +             return dev_err_probe(dev, PTR_ERR(clk), "devm_clk_get
> > failed\n");
> > +
> > +     ret = clk_prepare_enable(clk);
> > +     if (ret)
> > +             return dev_err_probe(dev, ret, "failed to enable
> > clock\n");
> > +
> > +     mpfs_gpio->clk = clk;
> > +
> > +     ngpio = of_irq_count(node);
> > +     if (ngpio > NUM_GPIO) {
> > +             ret = -ENXIO;
> > +             goto cleanup_clock;
> > +     }
> > +
> > +     irq_parent = of_irq_find_parent(node);
> > +     if (!irq_parent) {
> > +             ret = -ENODEV;
> > +             goto cleanup_clock;
> > +     }
> > +     parent = irq_find_host(irq_parent);
> > +     if (!parent) {
> > +             ret = -ENODEV;
> > +             goto cleanup_clock;
> > +     }
> > +
> > +     /* Get the interrupt numbers. */
> > +     /* Clear/Disable All interrupts before enabling parent
> > interrupts. */
> > +     for (i = 0; i < ngpio; i++) {
> > +             mpfs_gpio->irq_number[i] = platform_get_irq(pdev, i);
> 
> Bingo. You are allocating the interrupt for the level below. You
> really shouldn't do that.
> 
> If you need to retrieve the *hwirq* for the level below, you need to
> parse the DT without triggering an IRQ allocation (of_irq_parse_one()
> and co).
> 
>         M.
> 
> --
> Without deviation from the norm, progress is not possible.