RE: [PATCH 2/3 v3] dt-bindings: gpio: aspeed: Add SGPIO support
From: Hongwei Zhang
Date: Wed Jul 17 2019 - 17:30:05 EST
Hello Andrew,
Thanks for your review, please find the v4 in separate email. We merged all your suggestion in v4.
Best Regards,
--Hongwei
-----Original Message-----
> From: Andrew Jeffery <andrew@xxxxxxxx>
> Sent: Tuesday, July 16, 2019 11:26 PM
> To: Hongwei Zhang; Bartosz Golaszewski; Joel Stanley; Linus Walleij
> Cc: linux-gpio@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-aspeed@xxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 2/3 v3] ARM: dts: aspeed: Add SGPIO driver
>
> Hello Hongwei,
>
> Please send patches and feedback on prior iterations separately. Please send the output of `git format-
> patch ...`directly; format-patch spits the patch out in email form ready to go and can be fed straight to
> `git send-email`.
>
> On Wed, 17 Jul 2019, at 06:54, Hongwei Zhang wrote:
> > Add SGPIO driver support for Aspeed AST2500 SoC.
> >
> > Signed-off-by: Hongwei Zhang <hongweiz@xxxxxxx>
> > ---
> > drivers/gpio/sgpio-aspeed.c | 487
> > ++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 487 insertions(+)
> > create mode 100644 drivers/gpio/sgpio-aspeed.c
> >
> > diff --git a/drivers/gpio/sgpio-aspeed.c b/drivers/gpio/sgpio-aspeed.c
> > new file mode 100644 index 0000000..ade2cb7
> > --- /dev/null
> > +++ b/drivers/gpio/sgpio-aspeed.c
> > @@ -0,0 +1,487 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright 2019 American Megatrends International LLC.
> > + *
> > + * Author: Karthikeyan Mani <karthikeyanm@xxxxxxxxxxxxxx> */
> > +
> > +#include <linux/gpio/driver.h>
> > +#include <linux/gpio/aspeed.h>
>
> linux/gpio/aspeed.h is specific to the parallel GPIO driver, please drop this include.
>
Removed it.
> > +#include <linux/hashtable.h>
> > +#include <linux/bitfield.h>
> > +#include <linux/init.h>
> > +#include <linux/clk.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/pinctrl/consumer.h>
>
> This driver doesn't have any direct interaction with pinctrl, so I think we can remove this header
>
Removed it.
> > +#include <linux/platform_device.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/string.h>
> > +#include <linux/gpio.h>
> > +
> > +#define MAX_NR_SGPIO 80
> > +
> > +#define ASPEED_SGPIO_CTRL 0x54
> > +
> > +#define ASPEED_SGPIO_PINS_MASK GENMASK(9, 6)
> > +#define ASPEED_SGPIO_CLK_DIV_MASK GENMASK(31, 16)
> > +#define ASPEED_SGPIO_ENABLE BIT(0)
> > +
> > +// default sgpio direction is input.
> > +static uint32_t sgpio_dir_val[3] = {0xffffffff, 0xffffffff,
> > +0xffffffff
> > };
>
> Why not make it a member of struct aspeed_sgpio (below)? I'd prefer we encode the comment in the
> variable name as well, e.g.
> sgpio_dir_in`- this way when reading the code that uses it we know which bit state means what (set is
> input, clear is output).
>
Done.
> > +
> > +struct aspeed_sgpio {
> > + struct gpio_chip chip;
> > + struct clk *pclk;
> > + spinlock_t lock;
> > + void __iomem *base;
> > + int irq;
> > +};
> > +
> > +struct aspeed_sgpio_bank {
> > + uint16_t val_regs;
> > + uint16_t rdata_reg;
> > + uint16_t irq_regs;
> > + const char names[4][3];
> > +};
> > +
> > +/*
> > + * Note: The "value" register returns the input value sampled on the
> > + * line even when the GPIO is configured as an output. Since
> > + * that input goes through synchronizers, writing, then reading
> > + * back may not return the written value right away.
>
> The paragraph above is somewhat specific to the parallel GPIO driver.
> It would be good to rework it for the context of the SGPIO driver.
> Documenting the split of the "value" and "rdata" register is a good thing.
>
> > + *
> > + * The "rdata" register returns the content of the write latch
> > + * and thus can be used to read back what was last written
> > + * reliably.
> > + */
> > +static const struct aspeed_sgpio_bank aspeed_sgpio_banks[] = {
> > + {
> > + .val_regs = 0x0000,
> > + .rdata_reg = 0x0070,
> > + .irq_regs = 0x0004,
> > + .names = { "A", "B", "C", "D" },
> > + },
> > + {
> > + .val_regs = 0x001C,
> > + .rdata_reg = 0x0074,
> > + .irq_regs = 0x0020,
> > + .names = { "E", "F", "G", "H" },
> > + },
> > + {
> > + .val_regs = 0x0038,
> > + .rdata_reg = 0x0078,
> > + .irq_regs = 0x003C,
> > + .names = { "I", "J" },
> > + },
> > +};
> > +
> > +enum aspeed_sgpio_reg {
> > + reg_val,
> > + reg_rdata,
> > + reg_irq_enable,
> > + reg_irq_type0,
> > + reg_irq_type1,
> > + reg_irq_type2,
> > + reg_irq_status,
> > +};
> > +
> > +#define GPIO_VAL_VALUE 0x00
> > +#define GPIO_VAL_DIR 0x04
> > +#define GPIO_IRQ_ENABLE 0x00
> > +#define GPIO_IRQ_TYPE0 0x04
> > +#define GPIO_IRQ_TYPE1 0x08
> > +#define GPIO_IRQ_TYPE2 0x0C
> > +#define GPIO_IRQ_STATUS 0x10
> > +
> > +/* This will be resolved at compile time */ static inline void
> > +__iomem *bank_reg(struct aspeed_sgpio *gpio,
> > + const struct aspeed_sgpio_bank *bank,
> > + const enum aspeed_sgpio_reg reg) {
> > + switch (reg) {
> > + case reg_val:
> > + return gpio->base + bank->val_regs + GPIO_VAL_VALUE;
> > + case reg_rdata:
> > + return gpio->base + bank->rdata_reg;
> > + case reg_irq_enable:
> > + return gpio->base + bank->irq_regs + GPIO_IRQ_ENABLE;
> > + case reg_irq_type0:
> > + return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE0;
> > + case reg_irq_type1:
> > + return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE1;
> > + case reg_irq_type2:
> > + return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE2;
> > + case reg_irq_status:
> > + return gpio->base + bank->irq_regs + GPIO_IRQ_STATUS;
> > + default:
> > + /* acturally if code runs to here, it's an error case */
> > + BUG_ON(1);
> > + }
> > +}
> > +
> > +#define GPIO_BANK(x) ((x) >> 5)
> > +#define GPIO_OFFSET(x) ((x) & 0x1f)
> > +#define GPIO_BIT(x) BIT(GPIO_OFFSET(x))
> > +
> > +static const struct aspeed_sgpio_bank *to_bank(unsigned int offset) {
> > + unsigned int bank = GPIO_BANK(offset);
> > +
> > + WARN_ON(bank >= ARRAY_SIZE(aspeed_sgpio_banks));
> > + return &aspeed_sgpio_banks[bank];
> > +}
> > +
> > +static int aspeed_sgpio_get(struct gpio_chip *gc, unsigned int
> > +offset) {
> > + struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
> > + const struct aspeed_sgpio_bank *bank = to_bank(offset);
> > +
> > + if (sgpio_dir_val[GPIO_BANK(offset)] & GPIO_BIT(offset))
> > + return !!(ioread32(bank_reg(gpio, bank, reg_val)) &
> > GPIO_BIT(offset));
> > + else
> > + return !!(ioread32(bank_reg(gpio, bank, reg_rdata)) &
> > GPIO_BIT(offset));
>
> We don't need the else because we return from the body of the true case,
> and this could be written in a less redundant fashion. Also we need to do
> the read under gpio.lock for consistency with aspeed_sgpio_set().
>
> enum aspeed_sgpio_reg from;
> unsigned long flags;
> bool input;
> int rc;
>
> ...
>
> spin_lock_irqsave(&gpio->lock, flags);
> input = sgpio_dir_val[GPIO_BANK(offset)] & GPIO_BIT(offset);
> from = input ? reg_val : reg_rdata;
> rc = !!(ioread32(bank_reg(gpio, bank, from)) & GPIO_BIT(offset));
> spin_unlock_irqrestore(&gpio->lock, flags);
>
> return rc;
>
Updated code accordingly.
> > +
> > +}
> > +
> > +static void aspeed_sgpio_set(struct gpio_chip *gc, unsigned int
> > offset, int val)
> > +{
> > + struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
> > + const struct aspeed_sgpio_bank *bank = to_bank(offset);
> > + unsigned long flags;
> > + void __iomem *addr;
> > + u32 reg = 0;
> > +
> > + spin_lock_irqsave(&gpio->lock, flags);
> > +
> > + addr = bank_reg(gpio, bank, reg_val);
> > +
> > + if (val)
> > + reg |= GPIO_BIT(offset);
> > + else
> > + reg &= ~GPIO_BIT(offset);
> > +
> > + iowrite32(reg, addr);
> > + spin_unlock_irqrestore(&gpio->lock, flags);
> > +}
> > +
> > +static int aspeed_sgpio_dir_in(struct gpio_chip *gc, unsigned int
> > offset)
> > +{
> > + sgpio_dir_val[GPIO_BANK(offset)] |= GPIO_BIT(offset);
>
> Also do all manipulations of sgpio_dir_val under the spinlock.
>
Added spinlock as you suggested.
> > + return 0;
> > +}
> > +
> > +static int aspeed_sgpio_dir_out(struct gpio_chip *gc, unsigned int
> > offset, int val)
> > +{
> > + sgpio_dir_val[GPIO_BANK(offset)] &= ~GPIO_BIT(offset);
>
> Again here.
>
> > + return 0;
> > +}
> > +
> > +static int aspeed_sgpio_get_direction(struct gpio_chip *gc, unsigned
> > int offset)
> > +{
> > + return sgpio_dir_val[GPIO_BANK(offset)] & GPIO_BIT(offset);
>
> Again here.
>
> > +
> > +}
> > +
> > +static inline int irqd_to_aspeed_sgpio_data(struct irq_data *d,
> > + struct aspeed_sgpio **gpio,
> > + const struct aspeed_sgpio_bank **bank,
> > + u32 *bit, int *offset)
> > +{
> > + struct aspeed_sgpio *internal;
> > +
> > + *offset = irqd_to_hwirq(d);
> > +
> > + internal = irq_data_get_irq_chip_data(d);
> > +
> > + *gpio = internal;
> > + *bank = to_bank(*offset);
> > + *bit = GPIO_BIT(*offset);
> > +
> > + return 0;
>
> It looks like this function could be a void function instead, and we
> could eliminate error checking from the callsites. If you're feeling
> paranoid you could `WARN_ON(!internal);` after the call to
> `irq_data_get_irq_chip_data(d)`.
>
Updated.
> > +}
> > +
> > +static void aspeed_sgpio_irq_ack(struct irq_data *d)
> > +{
> > + const struct aspeed_sgpio_bank *bank;
> > + struct aspeed_sgpio *gpio;
> > + unsigned long flags;
> > + void __iomem *status_addr;
> > + int rc, offset;
> > + u32 bit;
> > +
> > + rc = irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
> > + if (rc)
> > + return;
> > +
> > + status_addr = bank_reg(gpio, bank, reg_irq_status);
> > +
> > + spin_lock_irqsave(&gpio->lock, flags);
> > +
> > + iowrite32(bit, status_addr);
> > +
> > + spin_unlock_irqrestore(&gpio->lock, flags);
> > +}
> > +
> > +static void aspeed_sgpio_irq_set_mask(struct irq_data *d, bool set)
> > +{
> > + const struct aspeed_sgpio_bank *bank;
> > + struct aspeed_sgpio *gpio;
> > + unsigned long flags;
> > + u32 reg, bit;
> > + void __iomem *addr;
> > + int rc, offset;
> > +
> > + rc = irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
> > + if (rc)
> > + return;
> > +
> > + addr = bank_reg(gpio, bank, reg_irq_enable);
> > +
> > + spin_lock_irqsave(&gpio->lock, flags);
> > +
> > + reg = ioread32(addr);
> > + if (set)
> > + reg |= bit;
> > + else
> > + reg &= ~bit;
> > +
> > + iowrite32(reg, addr);
> > +
> > + spin_unlock_irqrestore(&gpio->lock, flags);
> > +}
> > +
> > +static void aspeed_sgpio_irq_mask(struct irq_data *d)
> > +{
> > + aspeed_sgpio_irq_set_mask(d, false);
> > +}
> > +
> > +static void aspeed_sgpio_irq_unmask(struct irq_data *d)
> > +{
> > + aspeed_sgpio_irq_set_mask(d, true);
> > +}
> > +
> > +static int aspeed_sgpio_set_type(struct irq_data *d, unsigned int type)
> > +{
> > + u32 type0 = 0;
> > + u32 type1 = 0;
> > + u32 type2 = 0;
> > + u32 bit, reg;
> > + const struct aspeed_sgpio_bank *bank;
> > + irq_flow_handler_t handler;
> > + struct aspeed_sgpio *gpio;
> > + unsigned long flags;
> > + void __iomem *addr;
> > + int rc, offset;
> > +
> > + rc = irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
> > + if (rc)
> > + return -EINVAL;
> > +
> > + switch (type & IRQ_TYPE_SENSE_MASK) {
> > + case IRQ_TYPE_EDGE_BOTH:
> > + type2 |= bit;
> > + /* fall through */
> > + case IRQ_TYPE_EDGE_RISING:
> > + type0 |= bit;
> > + /* fall through */
> > + case IRQ_TYPE_EDGE_FALLING:
> > + handler = handle_edge_irq;
> > + break;
> > + case IRQ_TYPE_LEVEL_HIGH:
> > + type0 |= bit;
> > + /* fall through */
> > + case IRQ_TYPE_LEVEL_LOW:
> > + type1 |= bit;
> > + handler = handle_level_irq;
> > + break;
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + spin_lock_irqsave(&gpio->lock, flags);
> > +
> > + addr = bank_reg(gpio, bank, reg_irq_type0);
> > + reg = ioread32(addr);
> > + reg = (reg & ~bit) | type0;
> > + iowrite32(reg, addr);
> > +
> > + addr = bank_reg(gpio, bank, reg_irq_type1);
> > + reg = ioread32(addr);
> > + reg = (reg & ~bit) | type1;
> > + iowrite32(reg, addr);
> > +
> > + addr = bank_reg(gpio, bank, reg_irq_type2);
> > + reg = ioread32(addr);
> > + reg = (reg & ~bit) | type2;
> > + iowrite32(reg, addr);
> > +
> > + spin_unlock_irqrestore(&gpio->lock, flags);
> > +
> > + irq_set_handler_locked(d, handler);
> > +
> > + return 0;
> > +}
> > +
> > +static void aspeed_sgpio_irq_handler(struct irq_desc *desc)
> > +{
> > + struct gpio_chip *gc = irq_desc_get_handler_data(desc);
> > + struct irq_chip *ic = irq_desc_get_chip(desc);
> > + struct aspeed_sgpio *data = gpiochip_get_data(gc);
> > + unsigned int i, p, girq;
> > + unsigned long reg;
> > +
> > + chained_irq_enter(ic, desc);
> > +
> > + for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
> > + const struct aspeed_sgpio_bank *bank = &aspeed_sgpio_banks[i];
> > +
> > + reg = ioread32(bank_reg(data, bank, reg_irq_status));
> > +
> > + for_each_set_bit(p, ®, 32) {
> > + girq = irq_find_mapping(gc->irq.domain, i * 32 + p);
> > + generic_handle_irq(girq);
> > + }
> > +
> > + }
> > +
> > + chained_irq_exit(ic, desc);
> > +}
> > +
> > +static struct irq_chip aspeed_sgpio_irqchip = {
> > + .name = "aspeed-sgpio",
> > + .irq_ack = aspeed_sgpio_irq_ack,
> > + .irq_mask = aspeed_sgpio_irq_mask,
> > + .irq_unmask = aspeed_sgpio_irq_unmask,
> > + .irq_set_type = aspeed_sgpio_set_type,
> > +};
> > +
> > +static int aspeed_sgpio_setup_irqs(struct aspeed_sgpio *gpio,
> > + struct platform_device *pdev)
> > +{
> > + int rc, i;
> > + const struct aspeed_sgpio_bank *bank;
> > +
> > + rc = platform_get_irq(pdev, 0);
> > + if (rc < 0)
> > + return rc;
> > +
> > + gpio->irq = rc;
> > +
> > + /* Disable IRQ and clear Interrupt status registers for all SPGIO
> > Pins. */
> > + for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
> > + bank = &aspeed_sgpio_banks[i];
> > + /* disable irq enable bits */
> > + iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_enable));
> > + /* clear status bits */
> > + iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_status));
> > + }
> > +
> > + rc = gpiochip_irqchip_add(&gpio->chip, &aspeed_sgpio_irqchip,
> > + 0, handle_bad_irq, IRQ_TYPE_NONE);
> > + if (rc) {
> > + dev_info(&pdev->dev, "Could not add irqchip\n");
> > + return rc;
> > + }
> > +
> > + gpiochip_set_chained_irqchip(&gpio->chip, &aspeed_sgpio_irqchip,
> > + gpio->irq, aspeed_sgpio_irq_handler);
> > +
> > + /* set IRQ settings and Enable Interrupt */
> > + for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
> > + bank = &aspeed_sgpio_banks[i];
> > + /* set falling or level-low irq */
> > + iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type0));
> > + /* trigger type is edge */
> > + iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type1));
> > + /* dual edge trigger mode. */
> > + iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_type2));
> > + /* enable irq */
> > + iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_enable));
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id aspeed_sgpio_of_table[] = {
> > + { .compatible = "aspeed,ast2400-sgpio" },
> > + { .compatible = "aspeed,ast2500-sgpio" },
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(of, aspeed_sgpio_of_table);
> > +
> > +static int __init aspeed_sgpio_probe(struct platform_device *pdev)
> > +{
> > + struct aspeed_sgpio *gpio;
> > + struct resource *res;
> > + u32 nr_gpios, sgpio_freq;
> > + int rc;
> > + u16 sgpio_clk_div;
>
> Lets make this a u32 as it will help error detection below.
>
> > + unsigned long apb_freq;
> > +
> > + gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
> > + if (!gpio)
> > + return -ENOMEM;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + gpio->base = devm_ioremap_resource(&pdev->dev, res);
>
> Please use devm_platform_ioremap_resource() here.
>
> > + if (IS_ERR(gpio->base))
> > + return PTR_ERR(gpio->base);
> > +
> > + rc = of_property_read_u32(pdev->dev.of_node, "nr-gpios", &nr_gpios);
> > + if ((rc < 0) || (nr_gpios > MAX_NR_SGPIO))
> > + nr_gpios = MAX_NR_SGPIO;
>
> This is an error state, not something we should paper over. This should be
> `return -EINVAL;`
>
Updated.
> > +
> > + rc = of_property_read_u32(pdev->dev.of_node, "bus-frequency",
> > &sgpio_freq);
> > + if (rc < 0) {
> > + dev_err(&pdev->dev, "Could not read bus-frequency property\n");
> > + sgpio_freq = 12000000;
>
> Again, I suggested previously that this is a required property, not optional.
> As such there should not be fall-back code here. This is another case of
> `return -EINVAL;`.
>
Updated.
> > + }
> > +
> > + gpio->pclk = devm_clk_get(&pdev->dev, NULL);
> > + if (IS_ERR(gpio->pclk)) {
> > + dev_err(&pdev->dev, "devm_clk_get failed\n");
> > + return PTR_ERR(gpio->pclk);
> > + }
> > +
> > + apb_freq = clk_get_rate(gpio->pclk);
> > + sgpio_clk_div = 2 * ((apb_freq % sgpio_freq == 0) ?
> > + (apb_freq / sgpio_freq) - 1 : (apb_freq / sgpio_freq));
>
> This calculation seems overly complex and possibly incorrect (need to
> multiply the denominator or divide the result, not multiply the result)?
>
> From the datasheet, the SGPM clock period calculation is:
>
> period = 1/PCLK * 2 * (GPIO254[31:16] + 1)
>
> rearranging:
>
> period = 2 * (GPIO254[31:16] + 1) / PCLK
>
> Converting back to bus frequency:
>
> frequency = 1 / (2 * (GPIO254[31:16] + 1) / PCLK)
>
> Which rearranges to:
>
> frequency = PCLK / (2 * (GPIO254[31:16] + 1))
>
> Extracting GPIO254[31:16] in terms of PCLK / frequency from above:
>
> frequency * 2 * (GPIO254[31:16] + 1) = PCLK
>
> And so:
>
> GPIO254[31:16] = PCLK / (frequency * 2) - 1
>
> From that, the code should look something like:
>
> if (sgpio_freq == 0)
> return -EINVAL;
>
> sgpio_clk_div = apb_freq / (sgpio_freq * 2) - 1;
>
> if (sgpio_clk_div > (1 << 16) - 1)
> return -EINVAL;
>
> This seems to work at the extremes (sgpio_clk_div = 0 and
> sgpio_clk_div = 65535), and we get 32766.99 on a round-trip of
> the divider value 32768, which if we truncate gives an error of 0.023Hz
> with an APB of 24.75MHz (value reported from one of our boards).
>
> Andrew
>
Thanks for the formula and detailed suggestion, really appreciated.
> > + iowrite32(FIELD_PREP(ASPEED_SGPIO_CLK_DIV_MASK, sgpio_clk_div) |
> > + FIELD_PREP(ASPEED_SGPIO_PINS_MASK, (nr_gpios / 8)) |
> > + ASPEED_SGPIO_ENABLE,
> > + gpio->base + ASPEED_SGPIO_CTRL);
> > +
> > + spin_lock_init(&gpio->lock);
> > +
> > + gpio->chip.parent = &pdev->dev;
> > + gpio->chip.ngpio = nr_gpios;
> > + gpio->chip.direction_input = aspeed_sgpio_dir_in;
> > + gpio->chip.direction_output = aspeed_sgpio_dir_out;
> > + gpio->chip.get_direction = aspeed_sgpio_get_direction;
> > + gpio->chip.request = NULL;
> > + gpio->chip.free = NULL;
> > + gpio->chip.get = aspeed_sgpio_get;
> > + gpio->chip.set = aspeed_sgpio_set;
> > + gpio->chip.set_config = NULL;
> > + gpio->chip.label = dev_name(&pdev->dev);
> > + gpio->chip.base = ARCH_NR_GPIOS - MAX_NR_SGPIO;
> > +
> > + rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
> > + if (rc < 0)
> > + return rc;
> > +
> > + return aspeed_sgpio_setup_irqs(gpio, pdev);
> > +}
> > +
> > +static struct platform_driver aspeed_sgpio_driver = {
> > + .driver = {
> > + .name = KBUILD_MODNAME,
> > + .of_match_table = aspeed_sgpio_of_table,
> > + },
> > +};
> > +
> > +module_platform_driver_probe(aspeed_sgpio_driver, aspeed_sgpio_probe);
> > +MODULE_DESCRIPTION("Aspeed Serial GPIO Driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.7.4