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Date: Thu, 30 Jul 2020 18:45:47 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc: Hoan Tran <hoan@...amperecomputing.com>,
Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <bgolaszewski@...libre.com>,
Serge Semin <fancer.lancer@...il.com>,
Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
Rob Herring <robh+dt@...nel.org>, linux-gpio@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 05/10] gpio: dwapb: Convert driver to using the
GPIO-lib-based IRQ-chip
On Thu, Jul 30, 2020 at 06:28:02PM +0300, Serge Semin wrote:
> GPIO-lib provides a ready-to-use interface to initialize an IRQ-chip on
> top of a GPIO chip. It's better from maintainability and readability
> point of view to use one instead of supporting a hand-written Generic
> IRQ-chip-based implementation. Moreover the new implementation won't
> cause much functional overhead but will provide a cleaner driver code.
> All of that makes the DW APB GPIO driver conversion pretty much justified
> especially seeing a tendency of the other GPIO drivers getting converted
> too.
>
> Here is what we do in the framework of this commit to convert the driver
> to using the GPIO-lib-based IRQ-chip interface:
>
> 1) IRQ ack, mask and unmask callbacks are locally defined instead of
> using the Generic IRQ-chip ones.
>
> 2) An irq_chip structure instance is embedded into the dwapb_gpio
> private data. Note we can't have a static instance of that structure since
> GPIO-lib will add some hooks into it by calling gpiochip_set_irq_hooks().
> A warning about that would have been printed by the GPIO-lib code if we
> used a single irq_chip structure instance for multiple DW APB GPIO
> controllers.
>
> 3) Initialize the gpio_irq_chip structure embedded into the gpio_chip
> descriptor. By default there is no IRQ enabled so any event raised will be
> handled by the handle_bad_irq() IRQ flow handler. If DW APB GPIO IP-core
> is synthesized to have non-shared reference IRQ-lines, then as before the
> hierarchical and cascaded cases are distinguished by checking how many
> parental IRQs are defined. (Note irq_set_chained_handler_and_data() won't
> initialize IRQs, which descriptors couldn't be found.) If DW APB GPIO IP
> is used on a platform with shared IRQ line, then we simply won't let the
> GPIO-lib to initialize the parental IRQs, but will handle them locally in
> the driver.
>
> 4) Discard linear IRQ-domain and Generic IRQ-chip initialization, since
> GPIO-lib IRQ-chip interface will create a new domain and accept a standard
> IRQ-chip structure pointer based on the setting we provided in the
> gpio_irq_chip structure.
>
> 5) Manually select a proper IRQ flow handler directly in the
> irq_set_type() callback by calling irq_set_handler_locked() method, since
> an ordinary (not Generic) irq_chip descriptor is now utilized. Note this
> shalln't give any regression
>
> 6) Alter CONFIG_GPIO_DWAPB kernel config to select
> CONFIG_GPIOLIB_IRQCHIP instead of CONFIG_GENERIC_IRQ_CHIP.
>
> Note neither 4) nor 5) shall cause a regression of commit 6a2f4b7dadd5
> ("gpio: dwapb: use a second irq chip"), since the later isn't properly
> used here anyway.
Looks good, thanks!
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
>
> ---
>
> Note in this patch we omit the next GPIO-lib IRQ-chip settings
> initialization:
> gc->irq.map
> gc->irq.init_valid_mask
>
> That's intentionally done in order to keep the driver functionality at the
> same level as before the conversion: each GPIO line will be registered as
> the source of IRQs, no matter whether DW APB GPIO IP is configured to
> generate combined or multiple IRQ signals.
>
> If more thorough mapping is needed, the driver should be altered to detect
> the IRQ signaling mode (for instance by checking a dedicated DT-property).
> Then based on that it will be able to create a proper hardware GPIO-IRQ
> to/from parental IRQs mapping and valid hardware GPIO-IRQs mask.
>
> Changelog v2:
> - Replace gc->to_irq() with irq_find_mapping() method.
> - Refactor dwapb_irq_set_type() method to directly set IRQ flow handler
> instead of using a temporary variable.
> - Initialize GPIOlib IRQ-chip settings before calling request_irq()
> method.
> - Add a notice regarding regression of commit 6a2f4b7dadd5 ("gpio:
> dwapb: use a second irq chip").
> - Move the acpi_gpiochip_{request,free}_interrupts() methods invocation
> removal to a dedicated commit.
> - Move GPIO-chip to_irq callback removal to a dedicated commit.
> - Introduce dwapb_convert_irqs() method to convert the sparse parental
> IRQs array into an array of linearly distributed IRQs correctly
> perceived by GPIO-lib.
>
> Changelog v3:
> - Add blank lines to the commit message to make it more readable.
> - Dynamically allocate memory for the IRQ-chip-related data.
> ---
> drivers/gpio/Kconfig | 2 +-
> drivers/gpio/gpio-dwapb.c | 203 +++++++++++++++++++++-----------------
> 2 files changed, 111 insertions(+), 94 deletions(-)
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index c6b5c65c8405..bcd3e541a52b 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -202,7 +202,7 @@ config GPIO_DAVINCI
> config GPIO_DWAPB
> tristate "Synopsys DesignWare APB GPIO driver"
> select GPIO_GENERIC
> - select GENERIC_IRQ_CHIP
> + select GPIOLIB_IRQCHIP
> help
> Say Y or M here to build support for the Synopsys DesignWare APB
> GPIO block.
> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
> index f34001152850..eb3a6da453ff 100644
> --- a/drivers/gpio/gpio-dwapb.c
> +++ b/drivers/gpio/gpio-dwapb.c
> @@ -13,7 +13,6 @@
> #include <linux/io.h>
> #include <linux/ioport.h>
> #include <linux/irq.h>
> -#include <linux/irqdomain.h>
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> @@ -83,8 +82,15 @@ struct dwapb_context {
> };
> #endif
>
> +struct dwapb_gpio_port_irqchip {
> + struct irq_chip irqchip;
> + unsigned int nr_irqs;
> + unsigned int irq[DWAPB_MAX_GPIOS];
> +};
> +
> struct dwapb_gpio_port {
> struct gpio_chip gc;
> + struct dwapb_gpio_port_irqchip *pirq;
> bool is_registered;
> struct dwapb_gpio *gpio;
> #ifdef CONFIG_PM_SLEEP
> @@ -92,13 +98,14 @@ struct dwapb_gpio_port {
> #endif
> unsigned int idx;
> };
> +#define to_dwapb_gpio(_gc) \
> + (container_of(_gc, struct dwapb_gpio_port, gc)->gpio)
>
> struct dwapb_gpio {
> struct device *dev;
> void __iomem *regs;
> struct dwapb_gpio_port *ports;
> unsigned int nr_ports;
> - struct irq_domain *domain;
> unsigned int flags;
> struct reset_control *rst;
> struct clk_bulk_data clks[DWAPB_NR_CLOCKS];
> @@ -193,12 +200,13 @@ static void dwapb_toggle_trigger(struct dwapb_gpio *gpio, unsigned int offs)
>
> static u32 dwapb_do_irq(struct dwapb_gpio *gpio)
> {
> + struct gpio_chip *gc = &gpio->ports[0].gc;
> unsigned long irq_status;
> irq_hw_number_t hwirq;
>
> irq_status = dwapb_read(gpio, GPIO_INTSTATUS);
> for_each_set_bit(hwirq, &irq_status, DWAPB_MAX_GPIOS) {
> - int gpio_irq = irq_find_mapping(gpio->domain, hwirq);
> + int gpio_irq = irq_find_mapping(gc->irq.domain, hwirq);
> u32 irq_type = irq_get_trigger_type(gpio_irq);
>
> generic_handle_irq(gpio_irq);
> @@ -225,11 +233,48 @@ static irqreturn_t dwapb_irq_handler_mfd(int irq, void *dev_id)
> return IRQ_RETVAL(dwapb_do_irq(dev_id));
> }
>
> +static void dwapb_irq_ack(struct irq_data *d)
> +{
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> + u32 val = BIT(irqd_to_hwirq(d));
> + unsigned long flags;
> +
> + spin_lock_irqsave(&gc->bgpio_lock, flags);
> + dwapb_write(gpio, GPIO_PORTA_EOI, val);
> + spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +}
> +
> +static void dwapb_irq_mask(struct irq_data *d)
> +{
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> + unsigned long flags;
> + u32 val;
> +
> + spin_lock_irqsave(&gc->bgpio_lock, flags);
> + val = dwapb_read(gpio, GPIO_INTMASK) | BIT(irqd_to_hwirq(d));
> + dwapb_write(gpio, GPIO_INTMASK, val);
> + spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +}
> +
> +static void dwapb_irq_unmask(struct irq_data *d)
> +{
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> + unsigned long flags;
> + u32 val;
> +
> + spin_lock_irqsave(&gc->bgpio_lock, flags);
> + val = dwapb_read(gpio, GPIO_INTMASK) & ~BIT(irqd_to_hwirq(d));
> + dwapb_write(gpio, GPIO_INTMASK, val);
> + spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +}
> +
> static void dwapb_irq_enable(struct irq_data *d)
> {
> - struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> - struct dwapb_gpio *gpio = igc->private;
> - struct gpio_chip *gc = &gpio->ports[0].gc;
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> unsigned long flags;
> u32 val;
>
> @@ -242,9 +287,8 @@ static void dwapb_irq_enable(struct irq_data *d)
>
> static void dwapb_irq_disable(struct irq_data *d)
> {
> - struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> - struct dwapb_gpio *gpio = igc->private;
> - struct gpio_chip *gc = &gpio->ports[0].gc;
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> unsigned long flags;
> u32 val;
>
> @@ -257,9 +301,8 @@ static void dwapb_irq_disable(struct irq_data *d)
>
> static int dwapb_irq_set_type(struct irq_data *d, u32 type)
> {
> - struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> - struct dwapb_gpio *gpio = igc->private;
> - struct gpio_chip *gc = &gpio->ports[0].gc;
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> irq_hw_number_t bit = irqd_to_hwirq(d);
> unsigned long level, polarity, flags;
>
> @@ -293,7 +336,10 @@ static int dwapb_irq_set_type(struct irq_data *d, u32 type)
> break;
> }
>
> - irq_setup_alt_chip(d, type);
> + if (type & IRQ_TYPE_LEVEL_MASK)
> + irq_set_handler_locked(d, handle_level_irq);
> + else if (type & IRQ_TYPE_EDGE_BOTH)
> + irq_set_handler_locked(d, handle_edge_irq);
>
> dwapb_write(gpio, GPIO_INTTYPE_LEVEL, level);
> if (type != IRQ_TYPE_EDGE_BOTH)
> @@ -354,79 +400,67 @@ static int dwapb_gpio_set_config(struct gpio_chip *gc, unsigned offset,
> return dwapb_gpio_set_debounce(gc, offset, debounce);
> }
>
> +static int dwapb_convert_irqs(struct dwapb_gpio_port_irqchip *pirq,
> + struct dwapb_port_property *pp)
> +{
> + int i;
> +
> + /* Group all available IRQs into an array of parental IRQs. */
> + for (i = 0; i < pp->ngpio; ++i) {
> + if (!pp->irq[i])
> + continue;
> +
> + pirq->irq[pirq->nr_irqs++] = pp->irq[i];
> + }
> +
> + return pirq->nr_irqs ? 0 : -ENOENT;
> +}
> +
> static void dwapb_configure_irqs(struct dwapb_gpio *gpio,
> struct dwapb_gpio_port *port,
> struct dwapb_port_property *pp)
> {
> + struct dwapb_gpio_port_irqchip *pirq;
> struct gpio_chip *gc = &port->gc;
> - struct fwnode_handle *fwnode = pp->fwnode;
> - struct irq_chip_generic *irq_gc = NULL;
> - unsigned int ngpio = gc->ngpio;
> - struct irq_chip_type *ct;
> - irq_hw_number_t hwirq;
> - int err, i;
> -
> - if (memchr_inv(pp->irq, 0, sizeof(pp->irq)) == NULL) {
> - dev_warn(gpio->dev, "no IRQ for port%d\n", pp->idx);
> - return;
> - }
> -
> - gpio->domain = irq_domain_create_linear(fwnode, ngpio,
> - &irq_generic_chip_ops, gpio);
> - if (!gpio->domain)
> - return;
> + struct gpio_irq_chip *girq;
> + int err;
>
> - err = irq_alloc_domain_generic_chips(gpio->domain, ngpio, 2,
> - DWAPB_DRIVER_NAME, handle_bad_irq,
> - IRQ_NOREQUEST, 0,
> - IRQ_GC_INIT_NESTED_LOCK);
> - if (err) {
> - dev_info(gpio->dev, "irq_alloc_domain_generic_chips failed\n");
> - irq_domain_remove(gpio->domain);
> - gpio->domain = NULL;
> + pirq = devm_kzalloc(gpio->dev, sizeof(*pirq), GFP_KERNEL);
> + if (!pirq)
> return;
> - }
>
> - irq_gc = irq_get_domain_generic_chip(gpio->domain, 0);
> - if (!irq_gc) {
> - irq_domain_remove(gpio->domain);
> - gpio->domain = NULL;
> - return;
> + if (dwapb_convert_irqs(pirq, pp)) {
> + dev_warn(gpio->dev, "no IRQ for port%d\n", pp->idx);
> + goto err_kfree_pirq;
> }
>
> - irq_gc->reg_base = gpio->regs;
> - irq_gc->private = gpio;
> -
> - for (i = 0; i < 2; i++) {
> - ct = &irq_gc->chip_types[i];
> - ct->chip.irq_ack = irq_gc_ack_set_bit;
> - ct->chip.irq_mask = irq_gc_mask_set_bit;
> - ct->chip.irq_unmask = irq_gc_mask_clr_bit;
> - ct->chip.irq_set_type = dwapb_irq_set_type;
> - ct->chip.irq_enable = dwapb_irq_enable;
> - ct->chip.irq_disable = dwapb_irq_disable;
> + girq = &gc->irq;
> + girq->handler = handle_bad_irq;
> + girq->default_type = IRQ_TYPE_NONE;
> +
> + port->pirq = pirq;
> + pirq->irqchip.name = DWAPB_DRIVER_NAME;
> + pirq->irqchip.irq_ack = dwapb_irq_ack;
> + pirq->irqchip.irq_mask = dwapb_irq_mask;
> + pirq->irqchip.irq_unmask = dwapb_irq_unmask;
> + pirq->irqchip.irq_set_type = dwapb_irq_set_type;
> + pirq->irqchip.irq_enable = dwapb_irq_enable;
> + pirq->irqchip.irq_disable = dwapb_irq_disable;
> #ifdef CONFIG_PM_SLEEP
> - ct->chip.irq_set_wake = dwapb_irq_set_wake;
> + pirq->irqchip.irq_set_wake = dwapb_irq_set_wake;
> #endif
> - ct->regs.ack = gpio_reg_convert(gpio, GPIO_PORTA_EOI);
> - ct->regs.mask = gpio_reg_convert(gpio, GPIO_INTMASK);
> - ct->type = IRQ_TYPE_LEVEL_MASK;
> - }
> -
> - irq_gc->chip_types[0].type = IRQ_TYPE_LEVEL_MASK;
> - irq_gc->chip_types[0].handler = handle_level_irq;
> - irq_gc->chip_types[1].type = IRQ_TYPE_EDGE_BOTH;
> - irq_gc->chip_types[1].handler = handle_edge_irq;
>
> if (!pp->irq_shared) {
> - int i;
> -
> - for (i = 0; i < pp->ngpio; i++) {
> - if (pp->irq[i])
> - irq_set_chained_handler_and_data(pp->irq[i],
> - dwapb_irq_handler, gpio);
> - }
> + girq->num_parents = pirq->nr_irqs;
> + girq->parents = pirq->irq;
> + girq->parent_handler_data = gpio;
> + girq->parent_handler = dwapb_irq_handler;
> } else {
> + /* This will let us handle the parent IRQ in the driver */
> + girq->num_parents = 0;
> + girq->parents = NULL;
> + girq->parent_handler = NULL;
> +
> /*
> * Request a shared IRQ since where MFD would have devices
> * using the same irq pin
> @@ -436,33 +470,18 @@ static void dwapb_configure_irqs(struct dwapb_gpio *gpio,
> IRQF_SHARED, DWAPB_DRIVER_NAME, gpio);
> if (err) {
> dev_err(gpio->dev, "error requesting IRQ\n");
> - irq_domain_remove(gpio->domain);
> - gpio->domain = NULL;
> - return;
> + goto err_kfree_pirq;
> }
> }
>
> - for (hwirq = 0; hwirq < ngpio; hwirq++)
> - irq_create_mapping(gpio->domain, hwirq);
> + girq->chip = &pirq->irqchip;
>
> port->gc.to_irq = dwapb_gpio_to_irq;
> -}
> -
> -static void dwapb_irq_teardown(struct dwapb_gpio *gpio)
> -{
> - struct dwapb_gpio_port *port = &gpio->ports[0];
> - struct gpio_chip *gc = &port->gc;
> - unsigned int ngpio = gc->ngpio;
> - irq_hw_number_t hwirq;
> -
> - if (!gpio->domain)
> - return;
>
> - for (hwirq = 0; hwirq < ngpio; hwirq++)
> - irq_dispose_mapping(irq_find_mapping(gpio->domain, hwirq));
> + return;
>
> - irq_domain_remove(gpio->domain);
> - gpio->domain = NULL;
> +err_kfree_pirq:
> + devm_kfree(gpio->dev, pirq);
> }
>
> static int dwapb_gpio_add_port(struct dwapb_gpio *gpio,
> @@ -699,7 +718,6 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
>
> out_unregister:
> dwapb_gpio_unregister(gpio);
> - dwapb_irq_teardown(gpio);
> clk_bulk_disable_unprepare(DWAPB_NR_CLOCKS, gpio->clks);
>
> return err;
> @@ -710,7 +728,6 @@ static int dwapb_gpio_remove(struct platform_device *pdev)
> struct dwapb_gpio *gpio = platform_get_drvdata(pdev);
>
> dwapb_gpio_unregister(gpio);
> - dwapb_irq_teardown(gpio);
> reset_control_assert(gpio->rst);
> clk_bulk_disable_unprepare(DWAPB_NR_CLOCKS, gpio->clks);
>
> --
> 2.27.0
>
--
With Best Regards,
Andy Shevchenko
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