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Date: Wed, 13 Jul 2022 13:59:32 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: lewis.hanly@...rochip.com
Cc: "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
linux-riscv <linux-riscv@...ts.infradead.org>,
Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Palmer Dabbelt <palmer@...belt.com>,
Marc Zyngier <maz@...nel.org>, conor.dooley@...rochip.com,
daire.mcnamara@...rochip.com
Subject: Re: [PATCH v2 1/1] gpio: mpfs: add polarfire soc gpio support
On Wed, Jul 13, 2022 at 1:00 PM <lewis.hanly@...rochip.com> wrote:
>
> From: Lewis Hanly <lewis.hanly@...rochip.com>
>
> Add a driver to support the Polarfire SoC gpio controller.
GPIO
...
Below my comments, I have tried hard not to duplicate what Conor
already mentioned. So consider this as additional part.
...
> +config GPIO_POLARFIRE_SOC
> + bool "Microchip FPGA GPIO support"
Why not tristate?
> + depends on OF_GPIO
Why?
> + select GPIOLIB_IRQCHIP
> + select IRQ_DOMAIN_HIERARCHY
More naturally this line looks if put before GPIOLB_IRQCHIP one.
> + select GPIO_GENERIC
> + help
> + Say yes here to support the GPIO device on Microchip FPGAs.
When allowing it to be a module, add a text that tells how the driver
will be called.
...
> +/*
> + * Microchip PolarFire SoC (MPFS) GPIO controller driver
> + *
> + * Copyright (c) 2018-2022 Microchip Technology Inc. and its subsidiaries
> + *
> + * Author: Lewis Hanly <lewis.hanly@...rochip.com>
> + *
This line is not needed.
> + */
...
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
Why?
Also don't forget mod_devicetable.h.
...
> +#define NUM_GPIO 32
> +#define BYTE_BOUNDARY 0x04
Without namespace?
...
> + gpio_cfg = readl(mpfs_gpio->base + (gpio_index * BYTE_BOUNDARY));
> +
Unneeded line.
> + if (gpio_cfg & MPFS_GPIO_EN_IN)
> + return 1;
> +
> + return 0;
Don't we have specific definitions for the directions?
...
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
> + int gpio_index = irqd_to_hwirq(data);
> + u32 interrupt_type;
> + struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
This line naturally looks better before interrupt_type definition.
Try to keep the "longest line first" everywhere in the driver.
> + u32 gpio_cfg;
> + unsigned long flags;
...
> + switch (type) {
> + case IRQ_TYPE_EDGE_BOTH:
> + interrupt_type = MPFS_GPIO_TYPE_INT_EDGE_BOTH;
> + break;
> +
Unneeded line here and everywhere in the similar cases in the entire code.
> + case IRQ_TYPE_EDGE_FALLING:
> + interrupt_type = MPFS_GPIO_TYPE_INT_EDGE_NEG;
> + break;
> +
> + case IRQ_TYPE_EDGE_RISING:
> + interrupt_type = MPFS_GPIO_TYPE_INT_EDGE_POS;
> + break;
> +
> + case IRQ_TYPE_LEVEL_HIGH:
> + interrupt_type = MPFS_GPIO_TYPE_INT_LEVEL_HIGH;
> + break;
> +
> + case IRQ_TYPE_LEVEL_LOW:
> + interrupt_type = MPFS_GPIO_TYPE_INT_LEVEL_LOW;
> + break;
> + }
...
> + mpfs_gpio_assign_bit(mpfs_gpio->base + (gpio_index * BYTE_BOUNDARY),
> + MPFS_GPIO_EN_INT, 1);
Too many parentheses.
...
> + mpfs_gpio_assign_bit(mpfs_gpio->base + (gpio_index * BYTE_BOUNDARY),
> + MPFS_GPIO_EN_INT, 0);
Ditto.
...
> +static int mpfs_gpio_irq_set_affinity(struct irq_data *data,
> + const struct cpumask *dest,
> + bool force)
> +{
> + if (data->parent_data)
> + return irq_chip_set_affinity_parent(data, dest, force);
> +
> + return -EINVAL;
> +}
Why do you need this? Isn't it taken care of by the IRQ chip core?
...
> + struct clk *clk;
> + struct device *dev = &pdev->dev;
> + struct device_node *node = pdev->dev.of_node;
> + struct device_node *irq_parent;
Why do you need these?
> + struct gpio_irq_chip *girq;
> + struct irq_domain *parent;
> + struct mpfs_gpio_chip *mpfs_gpio;
> + int i, ret, ngpio;
...
> + clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(clk)) {
> + dev_err(&pdev->dev, "devm_clk_get failed\n");
> + return PTR_ERR(clk);
> + }
return dev_err_probe(...);
It's not only convenient, but here it fixes a bug.
> + ret = clk_prepare_enable(clk);
> + if (ret) {
> + dev_err(&pdev->dev, "failed to enable clock\n");
> + return ret;
return dev_err_probe(...);
> + }
Make it managed as well in addition to gpiochip_add_data(), otherwise
you will have wrong ordering.
...
> + ngpio = of_irq_count(node);
> + if (ngpio > NUM_GPIO) {
> + dev_err(dev, "Too many GPIO interrupts (max=%d)\n",
> + NUM_GPIO);
> + ret = -ENXIO;
> + goto cleanup_clock;
return dev_err_probe(...);
> + }
> +
> + irq_parent = of_irq_find_parent(node);
> + if (!irq_parent) {
> + dev_err(dev, "no IRQ parent node\n");
> + ret = -ENODEV;
> + goto cleanup_clock;
Ditto.
> + }
> + parent = irq_find_host(irq_parent);
> + if (!parent) {
> + dev_err(dev, "no IRQ parent domain\n");
> + ret = -ENODEV;
> + goto cleanup_clock;
Ditto.
> + }
Why do you need all these? Seems a copy'n'paste from gpio-sifive,
which is the only GPIO driver using this pattern.
...
> + mpfs_gpio_assign_bit(mpfs_gpio->base + (i * BYTE_BOUNDARY),
> + MPFS_GPIO_EN_INT, 0);
Too many parentheses.
> + girq->fwnode = of_node_to_fwnode(node);
This is an interesting way of
...->fwnode = dev_fwnode(dev);
...
> + dev_info(dev, "Microchip MPFS GPIO registered, ngpio=%d\n", ngpio);
Noise.
...
> + .of_match_table = of_match_ptr(mpfs_gpio_match),
Please, avoid using of_match_ptr(). It brings more harm than usefulness.
--
With Best Regards,
Andy Shevchenko
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