Re: [PATCH v3 1/3] gpio: nuvoton: Add Nuvoton NPCM7xx sgpio driver

Paul Menzel <pmenzel@xxxxxxxxxxxxx> · Tue, 20 Dec 2022 13:50:55 +0100

Dear Jim,


Thank you for the patch.

Am 20.12.22 um 09:01 schrieb Jim Liu:
Add Nuvoton BMC NPCM7xx sgpio driver support.

Please mention the datasheet, and how this is tested.

Signed-off-by: Jim Liu <JJLIU0@xxxxxxxxxxx>

The email address does not match the address the patch was sent from.

From the manual page git-send-email(1):

       --from=<address>
           Specify the sender of the emails. If not specified on the command
           line, the value of the sendemail.from configuration option is used.
           If neither the command-line option nor sendemail.from are set, then
           the user will be prompted for the value. The default for the prompt
           will be the value of GIT_AUTHOR_IDENT, or GIT_COMMITTER_IDENT if
           that is not set, as returned by "git var -l".

(To avoid having to press the shift key, lowercase local part would be 
nice: jjliu0@xxxxxxxxxxx. Depends on the server configuration though, if 
it’s the same address.)

---
Changes for v3:
    - remove return in bank_reg function
Changes for v2:
    - add prefix
    - write the enum values in all capitals
    - remove _init in npcm_sgpio_probe
---
  drivers/gpio/Kconfig           |   8 +
  drivers/gpio/Makefile          |   1 +
  drivers/gpio/gpio-npcm-sgpio.c | 639 +++++++++++++++++++++++++++++++++
  3 files changed, 648 insertions(+)
  create mode 100644 drivers/gpio/gpio-npcm-sgpio.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index ec7cfd4f52b1..c23fff243461 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -470,6 +470,14 @@ config GPIO_MXS
  	select GPIO_GENERIC
  	select GENERIC_IRQ_CHIP
  
+config GPIO_NPCM_SGPIO
+	bool "Nuvoton SGPIO support"
+	depends on (ARCH_NPCM || COMPILE_TEST) && OF_GPIO
+	select GPIO_GENERIC
+	select GPIOLIB_IRQCHIP
+	help
+	  Say Y here to support Nuvoton NPCM7XX/NPCM8XX SGPIO functionality.
+
  config GPIO_OCTEON
  	tristate "Cavium OCTEON GPIO"
  	depends on CAVIUM_OCTEON_SOC
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 010587025fc8..106146f383f3 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -111,6 +111,7 @@ obj-$(CONFIG_GPIO_MT7621)		+= gpio-mt7621.o
  obj-$(CONFIG_GPIO_MVEBU)		+= gpio-mvebu.o
  obj-$(CONFIG_GPIO_MXC)			+= gpio-mxc.o
  obj-$(CONFIG_GPIO_MXS)			+= gpio-mxs.o
+obj-$(CONFIG_GPIO_NPCM_SGPIO)           += gpio-npcm-sgpio.o
  obj-$(CONFIG_GPIO_OCTEON)		+= gpio-octeon.o
  obj-$(CONFIG_GPIO_OMAP)			+= gpio-omap.o
  obj-$(CONFIG_GPIO_PALMAS)		+= gpio-palmas.o
diff --git a/drivers/gpio/gpio-npcm-sgpio.c b/drivers/gpio/gpio-npcm-sgpio.c
new file mode 100644
index 000000000000..9c3896995f8f
--- /dev/null
+++ b/drivers/gpio/gpio-npcm-sgpio.c
@@ -0,0 +1,639 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NPCM Serial GPIO Driver
+ *
+ * Copyright (C) 2021 Nuvoton Technologies
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/gpio/driver.h>
+#include <linux/hashtable.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+#define MAX_NR_HW_SGPIO			64
+
+#define  NPCM_IOXCFG1				0x2A
+#define  NPCM_IOXCFG1_SFT_CLK		GENMASK(3, 0)
+#define  NPCM_IOXCFG1_SCLK_POL		BIT(4)
+#define  NPCM_IOXCFG1_LDSH_POL		BIT(5)
+
+#define  NPCM_IOXCTS 0x28
+#define  NPCM_IOXCTS_IOXIF_EN BIT(7)
+#define  NPCM_IOXCTS_RD_MODE GENMASK(2, 1)
+#define  NPCM_IOXCTS_RD_MODE_PERIODIC BIT(2)
+#define  NPCM_IOXCTS_RD_MODE_CONTINUOUS GENMASK(2, 1)
+
+#define  NPCM_IOXCFG2 0x2B
+#define  NPCM_IXOEVCFG_MASK 0x3
+#define  NPCM_IXOEVCFG_BOTH 0x3
+#define  NPCM_IXOEVCFG_FALLING 0x2
+#define  NPCM_IXOEVCFG_RISING 0x1
+
+#define GPIO_BANK(x)    ((x) / 8)
+#define GPIO_BIT(x)     ((x) % 8)
+
+/*
+ * Slect the freqency of shift clock.

Selectª.
2.  frequency

+ * The shift clock is a division of the APB clock.
+ */
+struct npcm_clk_cfg {
+	const int *SFT_CLK;
+	const u8 *CLK_SEL;
+	const u8 cfg_opt;
+};
+
+struct npcm_sgpio {
+	struct gpio_chip chip;
+	struct clk *pclk;
+	struct irq_chip intc;
+	spinlock_t lock; /*protect event config*/
+	void __iomem *base;
+	int irq;
+	u8 nin_sgpio;
+	u8 nout_sgpio;
+	u8 in_port;
+	u8 out_port;
+	u8 int_type[MAX_NR_HW_SGPIO];
+};
+
+struct npcm_sgpio_bank {
+	u8 rdata_reg;
+	u8 wdata_reg;
+	u8 event_config;
+	u8 event_status;
+};
+
+enum npcm_sgpio_reg {
+	READ_DATA,
+	WRITE_DATA,
+	EVENT_CFG,
+	EVENT_STS,
+};
+
+static const struct npcm_sgpio_bank npcm_sgpio_banks[] = {
+	{
+		.wdata_reg = 0x00,
+		.rdata_reg = 0x08,
+		.event_config = 0x10,
+		.event_status = 0x20,
+	},
+	{
+		.wdata_reg = 0x01,
+		.rdata_reg = 0x09,
+		.event_config = 0x12,
+		.event_status = 0x21,
+	},
+	{
+		.wdata_reg = 0x02,
+		.rdata_reg = 0x0a,
+		.event_config = 0x14,
+		.event_status = 0x22,
+	},
+	{
+		.wdata_reg = 0x03,
+		.rdata_reg = 0x0b,
+		.event_config = 0x16,
+		.event_status = 0x23,
+	},
+	{
+		.wdata_reg = 0x04,
+		.rdata_reg = 0x0c,
+		.event_config = 0x18,
+		.event_status = 0x24,
+	},
+	{
+		.wdata_reg = 0x05,
+		.rdata_reg = 0x0d,
+		.event_config = 0x1a,
+		.event_status = 0x25,
+	},
+	{
+		.wdata_reg = 0x06,
+		.rdata_reg = 0x0e,
+		.event_config = 0x1c,
+		.event_status = 0x26,
+	},
+	{
+		.wdata_reg = 0x07,
+		.rdata_reg = 0x0f,
+		.event_config = 0x1e,
+		.event_status = 0x27,
+	},
+
+};
+
+static void __iomem *bank_reg(struct npcm_sgpio *gpio,
+			      const struct npcm_sgpio_bank *bank,
+				const enum npcm_sgpio_reg reg)
+{
+	switch (reg) {
+	case READ_DATA:
+		return gpio->base + bank->rdata_reg;
+	case WRITE_DATA:
+		return gpio->base + bank->wdata_reg;
+	case EVENT_CFG:
+		return gpio->base + bank->event_config;
+	case EVENT_STS:
+		return gpio->base + bank->event_status;
+	default:
+		/* acturally if code runs to here, it's an error case */
+		WARN(1, "NPCM SGPIO REG SET failed!!\n");
+	}
+}
+
+static const struct npcm_sgpio_bank *to_bank(unsigned int offset)
+{
+	unsigned int bank = GPIO_BANK(offset);
+
+	return &npcm_sgpio_banks[bank];
+}
+
+static void irqd_to_npcm_sgpio_data(struct irq_data *d,
+				    struct npcm_sgpio **gpio,
+				    const struct npcm_sgpio_bank **bank,
+				    u8 *bit, int *offset)
+{
+	struct npcm_sgpio *internal;
+
+	*offset = irqd_to_hwirq(d);
+	internal = irq_data_get_irq_chip_data(d);
+	WARN_ON(!internal);
+
+	*gpio = internal;
+	*offset -= internal->nout_sgpio;
+	*bank = to_bank(*offset);
+	*bit = GPIO_BIT(*offset);
+}
+
+static int npcm_sgpio_init_valid_mask(struct gpio_chip *gc,
+				      unsigned long *valid_mask, unsigned int ngpios)
+{
+	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
+	u8 in_port, out_port, set_port;
+
+	in_port = gpio->nin_sgpio / 8;
+	if (gpio->nin_sgpio % 8 > 0)
+		in_port += 1;
+
+	out_port = gpio->nout_sgpio / 8;
+	if (gpio->nout_sgpio % 8 > 0)
+		out_port += 1;
+
+	gpio->in_port = in_port;
+	gpio->out_port = out_port;
+	set_port = ((out_port & 0xf) << 4) | (in_port & 0xf);
+	iowrite8(set_port, gpio->base + NPCM_IOXCFG2);
+
+	return 0;
+}
+
+static int npcm_sgpio_dir_in(struct gpio_chip *gc, unsigned int offset)
+{
+	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
+
+	if (offset < gpio->nout_sgpio)
+		return -EINVAL;
+
+	return 0;

If you like, you could write:

    return offset < gpio->nout_sgpio ? -EINVAL : 0;

+}
+
+static int npcm_sgpio_dir_out(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
+
+	if (offset < gpio->nout_sgpio) {
+		gc->set(gc, offset, val);
+		return 0;
+	}
+	return -EINVAL;

Above is a blank line before the `return` statement.

+}
+
+static int npcm_sgpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
+
+	if (offset < gpio->nout_sgpio)
+		return 0;
+	return 1;
+}
+
+static void npcm_sgpio_set(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
+	const struct  npcm_sgpio_bank *bank = to_bank(offset);
+	void __iomem *addr;
+	u8 reg = 0;
+
+	addr = bank_reg(gpio, bank, WRITE_DATA);
+	reg = ioread8(addr);
+
+	if (val) {
+		reg |= (val << GPIO_BIT(offset));
+		iowrite8(reg, addr);
+	} else {
+		reg &= ~(1 << GPIO_BIT(offset));
+		iowrite8(reg, addr);
+	}
+}
+
+static int npcm_sgpio_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
+	const struct  npcm_sgpio_bank *bank;
+	void __iomem *addr;
+	u8 dir, reg;
+
+	dir = npcm_sgpio_get_direction(gc, offset);

Is the variable `dir` needed? If yes, please use `int` as that is the 
type of the return value, and is more performant than fixed width type [1].

+	if (dir == 0) {
+		bank = to_bank(offset);
+
+		addr = bank_reg(gpio, bank, WRITE_DATA);
+		reg = ioread8(addr);
+		reg = (reg >> GPIO_BIT(offset)) & 0x01;
+	} else {
+		offset -= gpio->nout_sgpio;
+		bank = to_bank(offset);
+
+		addr = bank_reg(gpio, bank, READ_DATA);
+		reg = ioread8(addr);
+		reg = (reg >> GPIO_BIT(offset)) & 0x01;
+	}
+
+	return reg;
+}
+
+static void npcm_sgpio_setup_enable(struct npcm_sgpio *gpio, bool enable)
+{
+	u8 reg = 0;
+
+	reg = ioread8(gpio->base + NPCM_IOXCTS);
+	reg = reg & ~NPCM_IOXCTS_RD_MODE;
+	reg = reg | NPCM_IOXCTS_RD_MODE_PERIODIC;
+
+	if (enable) {
+		reg |= NPCM_IOXCTS_IOXIF_EN;
+		iowrite8(reg, gpio->base + NPCM_IOXCTS);
+	} else {
+		reg &= ~NPCM_IOXCTS_IOXIF_EN;
+		iowrite8(reg, gpio->base + NPCM_IOXCTS);
+	}
+}
+
+static int npcm_sgpio_setup_clk(struct npcm_sgpio *gpio,
+				const struct npcm_clk_cfg *clk_cfg, u32 sgpio_freq)
+{
+	unsigned long apb_freq;
+	u32 sgpio_clk_div;
+	u8 tmp;
+	int i;
+
+	apb_freq = clk_get_rate(gpio->pclk);
+	sgpio_clk_div = (apb_freq / sgpio_freq);
+	if ((apb_freq % sgpio_freq) != 0)
+		sgpio_clk_div += 1;
+
+	tmp = ioread8(gpio->base + NPCM_IOXCFG1) & ~NPCM_IOXCFG1_SFT_CLK;
+
+	for (i = 0; i < clk_cfg->cfg_opt; i++) {
+		if (sgpio_clk_div >= clk_cfg->SFT_CLK[i]) {
+			iowrite8(clk_cfg->CLK_SEL[i] | tmp, gpio->base + NPCM_IOXCFG1);
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static void npcm_sgpio_irq_init_valid_mask(struct gpio_chip *gc,
+					   unsigned long *valid_mask, unsigned int ngpios)
+{
+	struct npcm_sgpio *gpio = gpiochip_get_data(gc);
+	int n = gpio->nin_sgpio;
+
+	/* input GPIOs in the high range */
+	bitmap_set(valid_mask, gpio->nout_sgpio, n);
+	bitmap_clear(valid_mask, 0, gpio->nout_sgpio);
+}
+
+static void npcm_sgpio_irq_set_mask(struct irq_data *d, bool set)
+{
+	const struct npcm_sgpio_bank *bank;
+	struct npcm_sgpio *gpio;
+	unsigned long flags;
+	void __iomem *addr;
+	int offset;
+	u16 reg, type;
+	u8 bit;
+
+	irqd_to_npcm_sgpio_data(d, &gpio, &bank, &bit, &offset);
+	addr = bank_reg(gpio, bank, EVENT_CFG);
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	npcm_sgpio_setup_enable(gpio, false);
+
+	reg = ioread16(addr);
+	if (set) {
+		reg &= ~(NPCM_IXOEVCFG_MASK << (bit * 2));
+	} else {
+		type = gpio->int_type[offset];
+		reg |= (type << (bit * 2));
+	}
+
+	iowrite16(reg, addr);
+
+	npcm_sgpio_setup_enable(gpio, true);
+
+	addr = bank_reg(gpio, bank, EVENT_STS);
+	reg = ioread8(addr);
+	reg |= BIT(bit);
+	iowrite8(reg, addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static void npcm_sgpio_irq_ack(struct irq_data *d)
+{
+	const struct npcm_sgpio_bank *bank;
+	struct npcm_sgpio *gpio;
+	unsigned long flags;
+	void __iomem *status_addr;
+	int offset;
+	u8 bit;
+
+	irqd_to_npcm_sgpio_data(d, &gpio, &bank, &bit, &offset);
+	status_addr = bank_reg(gpio, bank, EVENT_STS);
+	spin_lock_irqsave(&gpio->lock, flags);
+	iowrite8(BIT(bit), status_addr);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static void npcm_sgpio_irq_mask(struct irq_data *d)
+{
+	npcm_sgpio_irq_set_mask(d, true);
+}
+
+static void npcm_sgpio_irq_unmask(struct irq_data *d)
+{
+	npcm_sgpio_irq_set_mask(d, false);
+}
+
+static int npcm_sgpio_set_type(struct irq_data *d, unsigned int type)
+{
+	const struct npcm_sgpio_bank *bank;
+	irq_flow_handler_t handler;
+	struct npcm_sgpio *gpio;
+	unsigned long flags;
+	void __iomem *addr;
+	int offset;
+	u16 reg, val;
+	u8 bit;
+
+	irqd_to_npcm_sgpio_data(d, &gpio, &bank, &bit, &offset);
+
+	switch (type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_EDGE_BOTH:
+		val = NPCM_IXOEVCFG_BOTH;
+		handler = handle_edge_irq;
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		val = NPCM_IXOEVCFG_RISING;
+		handler = handle_edge_irq;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		val = NPCM_IXOEVCFG_FALLING;
+		handler = handle_edge_irq;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		val = NPCM_IXOEVCFG_RISING;
+		handler = handle_level_irq;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		val = NPCM_IXOEVCFG_FALLING;
+		handler = handle_level_irq;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	gpio->int_type[offset] = val;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+	npcm_sgpio_setup_enable(gpio, false);
+	addr = bank_reg(gpio, bank, EVENT_CFG);
+	reg = ioread16(addr);
+
+	reg |= (val << (bit * 2));
+
+	iowrite16(reg, addr);
+	npcm_sgpio_setup_enable(gpio, true);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	irq_set_handler_locked(d, handler);
+
+	return 0;
+}
+
+static void npcm_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 npcm_sgpio *gpio = gpiochip_get_data(gc);
+	unsigned int i, j, girq;
+	unsigned long reg;
+
+	chained_irq_enter(ic, desc);
+
+	for (i = 0; i < ARRAY_SIZE(npcm_sgpio_banks); i++) {
+		const struct npcm_sgpio_bank *bank = &npcm_sgpio_banks[i];
+
+		reg = ioread8(bank_reg(gpio, bank, EVENT_STS));
+		for_each_set_bit(j, &reg, 8) {
+			girq = irq_find_mapping(gc->irq.domain, i * 8 + gpio->nout_sgpio + j);
+			generic_handle_irq(girq);
+		}
+	}
+
+	chained_irq_exit(ic, desc);
+}
+
+static int npcm_sgpio_setup_irqs(struct npcm_sgpio *gpio,
+				 struct platform_device *pdev)
+{
+	int rc, i;
+	struct gpio_irq_chip *irq;
+
+	rc = platform_get_irq(pdev, 0);
+	if (rc < 0)
+		return rc;
+
+	gpio->irq = rc;
+
+	npcm_sgpio_setup_enable(gpio, false);
+
+	/* Disable IRQ and clear Interrupt status registers for all SGPIO Pins. */
+	for (i = 0; i < ARRAY_SIZE(npcm_sgpio_banks); i++) {
+		const struct npcm_sgpio_bank *bank = &npcm_sgpio_banks[i];
+
+		iowrite16(0x0000, bank_reg(gpio, bank, EVENT_CFG));
+		iowrite8(0xff, bank_reg(gpio, bank, EVENT_STS));
+	}
+
+	gpio->intc.name = dev_name(&pdev->dev);
+	gpio->intc.irq_ack = npcm_sgpio_irq_ack;
+	gpio->intc.irq_mask = npcm_sgpio_irq_mask;
+	gpio->intc.irq_unmask = npcm_sgpio_irq_unmask;
+	gpio->intc.irq_set_type = npcm_sgpio_set_type;
+
+	irq = &gpio->chip.irq;
+	irq->chip = &gpio->intc;
+	irq->init_valid_mask = npcm_sgpio_irq_init_valid_mask;
+	irq->handler = handle_bad_irq;
+	irq->default_type = IRQ_TYPE_NONE;
+	irq->parent_handler = npcm_sgpio_irq_handler;
+	irq->parent_handler_data = gpio;
+	irq->parents = &gpio->irq;
+	irq->num_parents = 1;
+
+	return 0;
+}
+
+static const int npcm750_SFT_CLK[] = {
+		1024, 32, 8, 4, 3, 2,
+};
+
+static const u8 npcm750_CLK_SEL[] = {
+		0x00, 0x05, 0x07, 0x0C, 0x0D, 0x0E,
+};
+
+static const int npcm845_SFT_CLK[] = {
+		1024, 32, 16, 8, 4,
+};
+
+static const u8 npcm845_CLK_SEL[] = {
+		0x00, 0x05, 0x06, 0x07, 0x0C,
+};
+
+static const struct npcm_clk_cfg npcm750_sgpio_pdata = {
+	.SFT_CLK = npcm750_SFT_CLK,
+	.CLK_SEL = npcm750_CLK_SEL,
+	.cfg_opt = 6,
+};
+
+static const struct npcm_clk_cfg npcm845_sgpio_pdata = {

You do not mention NPCM845 in the commit message.

+	.SFT_CLK = npcm845_SFT_CLK,
+	.CLK_SEL = npcm845_CLK_SEL,
+	.cfg_opt = 5,
+};
+
+static const struct of_device_id npcm_sgpio_of_table[] = {
+	{ .compatible = "nuvoton,npcm750-sgpio", .data = &npcm750_sgpio_pdata, },
+	{ .compatible = "nuvoton,npcm845-sgpio", .data = &npcm845_sgpio_pdata, },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, npcm_sgpio_of_table);
+
+static int npcm_sgpio_probe(struct platform_device *pdev)
+{
+	struct npcm_sgpio *gpio;
+	const struct npcm_clk_cfg *clk_cfg;
+	int rc;
+	u32 nin_gpios, nout_gpios, sgpio_freq;
+
+	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(gpio->base))
+		return PTR_ERR(gpio->base);
+
+	clk_cfg = device_get_match_data(&pdev->dev);
+	if (!clk_cfg)
+		return -EINVAL;
+
+	rc = device_property_read_u32(&pdev->dev, "nin_gpios", &nin_gpios);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Could not read ngpios property\n");

Mention nin_gpios?

+		return -EINVAL;
+	}
+	rc = device_property_read_u32(&pdev->dev, "nout_gpios", &nout_gpios);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Could not read ngpios property\n");
+		return -EINVAL;
+	}
+
+	gpio->nin_sgpio = nin_gpios;
+	gpio->nout_sgpio = nout_gpios;
+	if (gpio->nin_sgpio > MAX_NR_HW_SGPIO || gpio->nout_sgpio > MAX_NR_HW_SGPIO) {
+		dev_err(&pdev->dev, "Number of GPIOs exceeds the maximum of %d: input: %d output: %d\n",
+			MAX_NR_HW_SGPIO, nin_gpios, nout_gpios);
+		return -EINVAL;
+	}
+
+	rc = device_property_read_u32(&pdev->dev, "bus-frequency", &sgpio_freq);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Could not read bus-frequency property\n");
+		return -EINVAL;
+	}
+
+	gpio->pclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(gpio->pclk)) {
+		dev_err(&pdev->dev, "devm_clk_get failed\n");

For a user, reading such an error message, I’d prefer a more elaborate 
message, for example, what won’t work, and that the serial GPIO driver 
initialization is aborted.

+		return PTR_ERR(gpio->pclk);
+	}
+
+	rc = npcm_sgpio_setup_clk(gpio, clk_cfg, sgpio_freq);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Failed to setup clock\n");
+		return -EINVAL;
+	}
+	spin_lock_init(&gpio->lock);
+	gpio->chip.parent = &pdev->dev;
+	gpio->chip.ngpio = gpio->nin_sgpio + gpio->nout_sgpio;
+	gpio->chip.init_valid_mask = npcm_sgpio_init_valid_mask;
+	gpio->chip.direction_input = npcm_sgpio_dir_in;
+	gpio->chip.direction_output = npcm_sgpio_dir_out;
+	gpio->chip.get_direction = npcm_sgpio_get_direction;
+	gpio->chip.request = NULL;
+	gpio->chip.free = NULL;
+	gpio->chip.get = npcm_sgpio_get;
+	gpio->chip.set = npcm_sgpio_set;
+	gpio->chip.set_config = NULL;
+	gpio->chip.label = dev_name(&pdev->dev);
+	gpio->chip.base = -1;
+
+	rc = npcm_sgpio_setup_irqs(gpio, pdev);
+	if (rc < 0)
+		return rc;
+
+	rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
+	if (rc < 0)
+		return rc;
+
+	npcm_sgpio_setup_enable(gpio, true);
+	return 0;
+}
+
+static struct platform_driver npcm_sgpio_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = npcm_sgpio_of_table,
+	},
+	.probe	= npcm_sgpio_probe,
+};
+
+module_platform_driver(npcm_sgpio_driver);
+
+MODULE_AUTHOR("Jim Liu <jjliu0@xxxxxxxxxxx>");
+MODULE_AUTHOR("Joseph Liu <kwliu@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Nuvoton NPCM Serial GPIO Driver");
+MODULE_LICENSE("GPL v2");


Kind regards,

Paul


[1]: https://notabs.org/coding/smallIntsBigPenalty.htm






