gpio: Remove dynamic allocation from populate_parent_alloc_arg()

The gpiolib is unique in the way it uses intermediate fwspecs
when feeding an interrupt specifier to the parent domain, as it
relies on the populate_parent_alloc_arg() callback to perform
a dynamic allocation.

This is pretty inefficient (we free the structure almost immediately),
and the only reason this isn't a stack allocation is that our
ThunderX friend uses MSIs rather than a FW-constructed structure.

Let's solve it by providing a new type composed of the union
of a struct irq_fwspec and a msi_info_t, which satisfies both
requirements. This allows us to use a stack allocation, and we
can move the handful of users to this new scheme.

Also perform some additional cleanup, such as getting rid of the
stub versions of the irq_domain_translate_*cell helpers, which
are never used when CONFIG_IRQ_DOMAIN_HIERARCHY isn't selected.

Tested on a Tegra186.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Daniel Palmer <daniel@thingy.jp>
Cc: Romain Perier <romain.perier@gmail.com>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Robert Richter <rric@kernel.org>
Cc: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
Link: https://lore.kernel.org/r/20220707182314.66610-2-prabhakar.mahadev-lad.rj@bp.renesas.com

diff --git a/drivers/gpio/gpio-msc313.c b/drivers/gpio/gpio-msc313.c
index b2c90bdd39d03ef2d993dab0cbd6496864df5d05..52d7b8d991705db4c79dabcf27dd641d44b16d3e 100644 (file)
--- a/drivers/gpio/gpio-msc313.c
+++ b/drivers/gpio/gpio-msc313.c
@@ -550,15 +550,12 @@ static struct irq_chip msc313_gpio_irqchip = {
  * so we need to provide the fwspec. Essentially gpiochip_populate_parent_fwspec_twocell
  * that puts GIC_SPI into the first cell.
  */
-static void *msc313_gpio_populate_parent_fwspec(struct gpio_chip *gc,
-                                            unsigned int parent_hwirq,
-                                            unsigned int parent_type)
+static int msc313_gpio_populate_parent_fwspec(struct gpio_chip *gc,
+                                             union gpio_irq_fwspec *gfwspec,
+                                             unsigned int parent_hwirq,
+                                             unsigned int parent_type)
 {
-       struct irq_fwspec *fwspec;
-
-       fwspec = kmalloc(sizeof(*fwspec), GFP_KERNEL);
-       if (!fwspec)
-               return NULL;
+       struct irq_fwspec *fwspec = &gfwspec->fwspec;
 
        fwspec->fwnode = gc->irq.parent_domain->fwnode;
        fwspec->param_count = 3;
@@ -566,7 +563,7 @@ static void *msc313_gpio_populate_parent_fwspec(struct gpio_chip *gc,
        fwspec->param[1] = parent_hwirq;
        fwspec->param[2] = parent_type;
 
-       return fwspec;
+       return 0;
 }
 
 static int msc313e_gpio_child_to_parent_hwirq(struct gpio_chip *chip,

diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c
index ff2d2a1f9c732dcb1b63f847c1d1a47af5e01adc..e4fb4cb38a0f4fa87fdabab753d15cc83ec737c9 100644 (file)
--- a/drivers/gpio/gpio-tegra.c
+++ b/drivers/gpio/gpio-tegra.c
@@ -443,15 +443,12 @@ static int tegra_gpio_child_to_parent_hwirq(struct gpio_chip *chip,
        return 0;
 }
 
-static void *tegra_gpio_populate_parent_fwspec(struct gpio_chip *chip,
-                                              unsigned int parent_hwirq,
-                                              unsigned int parent_type)
+static int tegra_gpio_populate_parent_fwspec(struct gpio_chip *chip,
+                                            union gpio_irq_fwspec *gfwspec,
+                                            unsigned int parent_hwirq,
+                                            unsigned int parent_type)
 {
-       struct irq_fwspec *fwspec;
-
-       fwspec = kmalloc(sizeof(*fwspec), GFP_KERNEL);
-       if (!fwspec)
-               return NULL;
+       struct irq_fwspec *fwspec = &gfwspec->fwspec;
 
        fwspec->fwnode = chip->irq.parent_domain->fwnode;
        fwspec->param_count = 3;
@@ -459,7 +456,7 @@ static void *tegra_gpio_populate_parent_fwspec(struct gpio_chip *chip,
        fwspec->param[1] = parent_hwirq;
        fwspec->param[2] = parent_type;
 
-       return fwspec;
+       return 0;
 }
 
 #ifdef CONFIG_PM_SLEEP

diff --git a/drivers/gpio/gpio-tegra186.c b/drivers/gpio/gpio-tegra186.c
index de28a68daea0d4d538fe256fe5238df16e835cc2..54d9fa7da9c1ea98e3f6ef2b0362758e2f5de756 100644 (file)
--- a/drivers/gpio/gpio-tegra186.c
+++ b/drivers/gpio/gpio-tegra186.c
@@ -621,16 +621,13 @@ static int tegra186_gpio_irq_domain_translate(struct irq_domain *domain,
        return 0;
 }
 
-static void *tegra186_gpio_populate_parent_fwspec(struct gpio_chip *chip,
-                                                unsigned int parent_hwirq,
-                                                unsigned int parent_type)
+static int tegra186_gpio_populate_parent_fwspec(struct gpio_chip *chip,
+                                               union gpio_irq_fwspec *gfwspec,
+                                               unsigned int parent_hwirq,
+                                               unsigned int parent_type)
 {
        struct tegra_gpio *gpio = gpiochip_get_data(chip);
-       struct irq_fwspec *fwspec;
-
-       fwspec = kmalloc(sizeof(*fwspec), GFP_KERNEL);
-       if (!fwspec)
-               return NULL;
+       struct irq_fwspec *fwspec = &gfwspec->fwspec;
 
        fwspec->fwnode = chip->irq.parent_domain->fwnode;
        fwspec->param_count = 3;
@@ -638,7 +635,7 @@ static void *tegra186_gpio_populate_parent_fwspec(struct gpio_chip *chip,
        fwspec->param[1] = parent_hwirq;
        fwspec->param[2] = parent_type;
 
-       return fwspec;
+       return 0;
 }
 
 static int tegra186_gpio_child_to_parent_hwirq(struct gpio_chip *chip,

diff --git a/drivers/gpio/gpio-thunderx.c b/drivers/gpio/gpio-thunderx.c
index 9f66deab46eaa99d05413a996b585284c433574d..e1dedbca0c852d6af6e06b33075d54fb859c1e2a 100644 (file)
--- a/drivers/gpio/gpio-thunderx.c
+++ b/drivers/gpio/gpio-thunderx.c
@@ -408,18 +408,15 @@ static int thunderx_gpio_child_to_parent_hwirq(struct gpio_chip *gc,
        return 0;
 }
 
-static void *thunderx_gpio_populate_parent_alloc_info(struct gpio_chip *chip,
-                                                     unsigned int parent_hwirq,
-                                                     unsigned int parent_type)
+static int thunderx_gpio_populate_parent_alloc_info(struct gpio_chip *chip,
+                                                   union gpio_irq_fwspec *gfwspec,
+                                                   unsigned int parent_hwirq,
+                                                   unsigned int parent_type)
 {
-       msi_alloc_info_t *info;
-
-       info = kmalloc(sizeof(*info), GFP_KERNEL);
-       if (!info)
-               return NULL;
+       msi_alloc_info_t *info = &gfwspec->msiinfo;
 
        info->hwirq = parent_hwirq;
-       return info;
+       return 0;
 }
 
 static int thunderx_gpio_probe(struct pci_dev *pdev,

diff --git a/drivers/gpio/gpio-visconti.c b/drivers/gpio/gpio-visconti.c
index e6534ea1eaa7a21968d1793c172a0f54daad87ea..5e108ba9956a6c28cdfb1ee53df0830dd9265168 100644 (file)
--- a/drivers/gpio/gpio-visconti.c
+++ b/drivers/gpio/gpio-visconti.c
@@ -103,15 +103,12 @@ static int visconti_gpio_child_to_parent_hwirq(struct gpio_chip *gc,
        return -EINVAL;
 }
 
-static void *visconti_gpio_populate_parent_fwspec(struct gpio_chip *chip,
-                                                 unsigned int parent_hwirq,
-                                                 unsigned int parent_type)
+static int visconti_gpio_populate_parent_fwspec(struct gpio_chip *chip,
+                                               union gpio_irq_fwspec *gfwspec,
+                                               unsigned int parent_hwirq,
+                                               unsigned int parent_type)
 {
-       struct irq_fwspec *fwspec;
-
-       fwspec = kmalloc(sizeof(*fwspec), GFP_KERNEL);
-       if (!fwspec)
-               return NULL;
+       struct irq_fwspec *fwspec = &gfwspec->fwspec;
 
        fwspec->fwnode = chip->irq.parent_domain->fwnode;
        fwspec->param_count = 3;
@@ -119,7 +116,7 @@ static void *visconti_gpio_populate_parent_fwspec(struct gpio_chip *chip,
        fwspec->param[1] = parent_hwirq;
        fwspec->param[2] = parent_type;
 
-       return fwspec;
+       return 0;
 }
 
 static int visconti_gpio_probe(struct platform_device *pdev)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 9535f48e18d1c8befd987512341cb148046fc8c5..bfde94243752c76f83fc10f3bfe42c3036bef929 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1107,7 +1107,7 @@ static int gpiochip_hierarchy_irq_domain_alloc(struct irq_domain *d,
        irq_hw_number_t hwirq;
        unsigned int type = IRQ_TYPE_NONE;
        struct irq_fwspec *fwspec = data;
-       void *parent_arg;
+       union gpio_irq_fwspec gpio_parent_fwspec = {};
        unsigned int parent_hwirq;
        unsigned int parent_type;
        struct gpio_irq_chip *girq = &gc->irq;
@@ -1147,14 +1147,15 @@ static int gpiochip_hierarchy_irq_domain_alloc(struct irq_domain *d,
        irq_set_probe(irq);
 
        /* This parent only handles asserted level IRQs */
-       parent_arg = girq->populate_parent_alloc_arg(gc, parent_hwirq, parent_type);
-       if (!parent_arg)
-               return -ENOMEM;
+       ret = girq->populate_parent_alloc_arg(gc, &gpio_parent_fwspec,
+                                             parent_hwirq, parent_type);
+       if (ret)
+               return ret;
 
        chip_dbg(gc, "alloc_irqs_parent for %d parent hwirq %d\n",
                  irq, parent_hwirq);
        irq_set_lockdep_class(irq, gc->irq.lock_key, gc->irq.request_key);
-       ret = irq_domain_alloc_irqs_parent(d, irq, 1, parent_arg);
+       ret = irq_domain_alloc_irqs_parent(d, irq, 1, &gpio_parent_fwspec);
        /*
         * If the parent irqdomain is msi, the interrupts have already
         * been allocated, so the EEXIST is good.
@@ -1166,7 +1167,6 @@ static int gpiochip_hierarchy_irq_domain_alloc(struct irq_domain *d,
                         "failed to allocate parent hwirq %d for hwirq %lu\n",
                         parent_hwirq, hwirq);
 
-       kfree(parent_arg);
        return ret;
 }
 
@@ -1230,34 +1230,28 @@ static bool gpiochip_hierarchy_is_hierarchical(struct gpio_chip *gc)
        return !!gc->irq.parent_domain;
 }
 
-void *gpiochip_populate_parent_fwspec_twocell(struct gpio_chip *gc,
-                                            unsigned int parent_hwirq,
-                                            unsigned int parent_type)
+int gpiochip_populate_parent_fwspec_twocell(struct gpio_chip *gc,
+                                           union gpio_irq_fwspec *gfwspec,
+                                           unsigned int parent_hwirq,
+                                           unsigned int parent_type)
 {
-       struct irq_fwspec *fwspec;
-
-       fwspec = kmalloc(sizeof(*fwspec), GFP_KERNEL);
-       if (!fwspec)
-               return NULL;
+       struct irq_fwspec *fwspec = &gfwspec->fwspec;
 
        fwspec->fwnode = gc->irq.parent_domain->fwnode;
        fwspec->param_count = 2;
        fwspec->param[0] = parent_hwirq;
        fwspec->param[1] = parent_type;
 
-       return fwspec;
+       return 0;
 }
 EXPORT_SYMBOL_GPL(gpiochip_populate_parent_fwspec_twocell);
 
-void *gpiochip_populate_parent_fwspec_fourcell(struct gpio_chip *gc,
-                                             unsigned int parent_hwirq,
-                                             unsigned int parent_type)
+int gpiochip_populate_parent_fwspec_fourcell(struct gpio_chip *gc,
+                                            union gpio_irq_fwspec *gfwspec,
+                                            unsigned int parent_hwirq,
+                                            unsigned int parent_type)
 {
-       struct irq_fwspec *fwspec;
-
-       fwspec = kmalloc(sizeof(*fwspec), GFP_KERNEL);
-       if (!fwspec)
-               return NULL;
+       struct irq_fwspec *fwspec = &gfwspec->fwspec;
 
        fwspec->fwnode = gc->irq.parent_domain->fwnode;
        fwspec->param_count = 4;
@@ -1266,7 +1260,7 @@ void *gpiochip_populate_parent_fwspec_fourcell(struct gpio_chip *gc,
        fwspec->param[2] = 0;
        fwspec->param[3] = parent_type;
 
-       return fwspec;
+       return 0;
 }
 EXPORT_SYMBOL_GPL(gpiochip_populate_parent_fwspec_fourcell);
 

diff --git a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
index fd5fff9adff083e64b734253f4c65b3902035266..3be2a08ae3a6aab5d4c798b9ef4f8e842793f724 100644 (file)
--- a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
+++ b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
@@ -966,16 +966,13 @@ static int pmic_gpio_child_to_parent_hwirq(struct gpio_chip *chip,
        return 0;
 }
 
-static void *pmic_gpio_populate_parent_fwspec(struct gpio_chip *chip,
-                                            unsigned int parent_hwirq,
-                                            unsigned int parent_type)
+static int pmic_gpio_populate_parent_fwspec(struct gpio_chip *chip,
+                                           union gpio_irq_fwspec *gfwspec,
+                                           unsigned int parent_hwirq,
+                                           unsigned int parent_type)
 {
        struct pmic_gpio_state *state = gpiochip_get_data(chip);
-       struct irq_fwspec *fwspec;
-
-       fwspec = kzalloc(sizeof(*fwspec), GFP_KERNEL);
-       if (!fwspec)
-               return NULL;
+       struct irq_fwspec *fwspec = &gfwspec->fwspec;
 
        fwspec->fwnode = chip->irq.parent_domain->fwnode;
 
@@ -985,7 +982,7 @@ static void *pmic_gpio_populate_parent_fwspec(struct gpio_chip *chip,
        /* param[2] must be left as 0 */
        fwspec->param[3] = parent_type;
 
-       return fwspec;
+       return 0;
 }
 
 static int pmic_gpio_probe(struct platform_device *pdev)

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index b1e0f1f8ee2e70d327aa50a6da9e196457aa502f..ad5b92b74ccf9857cd73615215e26a9ef16bbdf4 100644 (file)
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -12,6 +12,8 @@
 #include <linux/property.h>
 #include <linux/types.h>
 
+#include <asm/msi.h>
+
 struct gpio_desc;
 struct of_phandle_args;
 struct device_node;
@@ -23,6 +25,13 @@ enum gpio_lookup_flags;
 
 struct gpio_chip;
 
+union gpio_irq_fwspec {
+       struct irq_fwspec       fwspec;
+#ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
+       msi_alloc_info_t        msiinfo;
+#endif
+};
+
 #define GPIO_LINE_DIRECTION_IN 1
 #define GPIO_LINE_DIRECTION_OUT        0
 
@@ -103,9 +112,10 @@ struct gpio_irq_chip {
         * variant named &gpiochip_populate_parent_fwspec_fourcell is also
         * available.
         */
-       void *(*populate_parent_alloc_arg)(struct gpio_chip *gc,
-                                      unsigned int parent_hwirq,
-                                      unsigned int parent_type);
+       int (*populate_parent_alloc_arg)(struct gpio_chip *gc,
+                                        union gpio_irq_fwspec *fwspec,
+                                        unsigned int parent_hwirq,
+                                        unsigned int parent_type);
 
        /**
         * @child_offset_to_irq:
@@ -646,28 +656,14 @@ struct bgpio_pdata {
 
 #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
 
-void *gpiochip_populate_parent_fwspec_twocell(struct gpio_chip *gc,
+int gpiochip_populate_parent_fwspec_twocell(struct gpio_chip *gc,
+                                           union gpio_irq_fwspec *gfwspec,
+                                           unsigned int parent_hwirq,
+                                           unsigned int parent_type);
+int gpiochip_populate_parent_fwspec_fourcell(struct gpio_chip *gc,
+                                            union gpio_irq_fwspec *gfwspec,
                                             unsigned int parent_hwirq,
                                             unsigned int parent_type);
-void *gpiochip_populate_parent_fwspec_fourcell(struct gpio_chip *gc,
-                                             unsigned int parent_hwirq,
-                                             unsigned int parent_type);
-
-#else
-
-static inline void *gpiochip_populate_parent_fwspec_twocell(struct gpio_chip *gc,
-                                                   unsigned int parent_hwirq,
-                                                   unsigned int parent_type)
-{
-       return NULL;
-}
-
-static inline void *gpiochip_populate_parent_fwspec_fourcell(struct gpio_chip *gc,
-                                                    unsigned int parent_hwirq,
-                                                    unsigned int parent_type)
-{
-       return NULL;
-}
 
 #endif /* CONFIG_IRQ_DOMAIN_HIERARCHY */