Re: [PATCH v3] serial: 8250: add gpio support to exar

Andy Shevchenko
2015-12-20T14:18:21Z

On Sun, Dec 20, 2015 at 3:24 PM, Sudip Mukherjee
<sudipm.mukherjee@gmail.com> wrote:
> Exar XR17V352/354/358 chips have 16 multi-purpose inputs/outputs which
> can be controlled using gpio interface.
> Add support to use these pins and select GPIO_SYSFS also so that these
> pins can be used from the userspace through sysfs.
>
> Tested-by: Rob Groner <rgroner@rtd.com>
> Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>

> @@ -0,0 +1,261 @@
> +/*
> + * GPIO driver for Exar XR17V35X chip
> + *
> + * Copyright (C) 2015 Sudip Mukherjee <sudipm.mukherjee@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/pci.h>
> +#include <linux/gpio.h>
> +#include "8250.h"
> +
> +#define EXAR_OFFSET_MPIOLVL_LO 0x90
> +#define EXAR_OFFSET_MPIOSEL_LO 0x93
> +#define EXAR_OFFSET_MPIOLVL_HI 0x96
> +#define EXAR_OFFSET_MPIOSEL_HI 0x99
> +
> +static LIST_HEAD(exar_list);
> +static DEFINE_MUTEX(exar_mtx); /* lock while manipulating the list */
> +
> +struct exar_gpio_chip {
> + struct gpio_chip gpio_chip;
> + struct mutex lock;
> + struct uart_8250_port *port;
> + struct list_head list;
> + int index;
> + void __iomem *regs;
> + char name[16];
> +};
> +
> +#define to_exar_chip(n) container_of(n, struct exar_gpio_chip, gpio_chip)
> +
> +static inline unsigned int read_exar_reg(struct exar_gpio_chip *chip,
> + int offset)
> +{
> + pr_debug("%s regs=%p offset=%x\n", __func__, chip->regs, offset);

dev_dbg()

> + return readb(chip->regs + offset);
> +}
> +
> +static inline void write_exar_reg(struct exar_gpio_chip *chip, int offset,
> + int value)
> +{
> + pr_debug("%s regs=%p value=%x offset=%x\n", __func__, chip->regs,
> + value, offset);

Ditto.

> + writeb(value, chip->regs + offset);
> +}
> +
> +void xr17v35x_gpio_exit(struct uart_8250_port *port)
> +{
> + struct exar_gpio_chip *exar_gpio, *exar_temp1, *exar_temp2;

I would suggest to use *e, *_e for temporary variables.

> +
> + if (!port)
> + return;
> +
> + exar_gpio = port->port.private_data;
> + if (!exar_gpio)
> + return;

Maybe
if (!port || !port->port.private_data)
return;

exar_gpio = port->port.private_data;
mutex_lock(&exar_mtx);

> + list_for_each_entry_safe(exar_temp1, exar_temp2, &exar_list, list) {
> + if (exar_temp1->index == exar_gpio->index) {
> + list_del(&exar_temp1->list);
> + break;
> + }
> + }
> + mutex_unlock(&exar_mtx);
> +
> + gpiochip_remove(&exar_gpio->gpio_chip);
> + mutex_destroy(&exar_gpio->lock);
> + iounmap(exar_gpio->regs);
> +}
> +EXPORT_SYMBOL(xr17v35x_gpio_exit);
> +
> +static void exar_set(struct gpio_chip *chip, unsigned int reg, int val,
> + unsigned int offset)

Perhaps …, unsigned int offset, int val)

> +{
> + struct exar_gpio_chip *exar_gpio = to_exar_chip(chip);
> + int temp;
> +
> + mutex_lock(&exar_gpio->lock);
> + temp = read_exar_reg(exar_gpio, reg);
> + temp &= ~(1 << offset);
> + temp |= val << offset;
> + write_exar_reg(exar_gpio, reg, temp);
> + mutex_unlock(&exar_gpio->lock);
> +}
> +
> +static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
> + int value)
> +{
> + if (offset < 8)
> + exar_set(chip, EXAR_OFFSET_MPIOSEL_LO, 0, offset);
> + else
> + exar_set(chip, EXAR_OFFSET_MPIOSEL_HI, 0, offset - 8);
> + return 0;
> +}
> +
> +static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
> +{
> + if (offset < 8)
> + exar_set(chip, EXAR_OFFSET_MPIOSEL_LO, 1, offset);
> + else
> + exar_set(chip, EXAR_OFFSET_MPIOSEL_HI, 1, offset - 8);
> + return 0;
> +}
> +
> +static int exar_get(struct gpio_chip *chip, unsigned int reg)
> +{
> + int value;
> + struct exar_gpio_chip *exar_gpio = to_exar_chip(chip);

Perhaps exchange positions of the lines to be assignment first,
uninitialized — second.

> +
> + if (!exar_gpio) {
> + pr_err("%s exar_gpio is NULL\n", __func__);

I doubt it's useful message.

> + return -ENOMEM;
> + }
> +
> + mutex_lock(&exar_gpio->lock);
> + value = read_exar_reg(exar_gpio, reg);
> + mutex_unlock(&exar_gpio->lock);
> +
> + return value;
> +}
> +
> +static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
> +{
> + int val;

int value; like you have elsewhere.

> +
> + if (offset < 8) {
> + val = exar_get(chip, EXAR_OFFSET_MPIOSEL_LO);
> + } else {
> + val = exar_get(chip, EXAR_OFFSET_MPIOSEL_HI);
> + offset -= 8;
> + }
> +
> + if (val > 0) {
> + val >>= offset;
> + val &= 0x01;
> + }
> +
> + return val;
> +}
> +
> +static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
> +{
> + int val;

Ditto.

> +
> + if (offset < 8) {
> + val = exar_get(chip, EXAR_OFFSET_MPIOLVL_LO);
> + } else {
> + val = exar_get(chip, EXAR_OFFSET_MPIOLVL_HI);
> + offset -= 8;
> + }
> + val >>= offset;
> + val &= 0x01;
> +
> + return val;
> +}
> +
> +static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
> + int value)

Yep, offset before value!

> +{
> + if (offset < 8)
> + exar_set(chip, EXAR_OFFSET_MPIOLVL_LO, value, offset);
> + else
> + exar_set(chip, EXAR_OFFSET_MPIOLVL_HI, value, offset - 8);
> +}
> +
> +int xr17v35x_gpio_init(struct pci_dev *dev, struct uart_8250_port *port,
> + int idx)
> +{
> + struct exar_gpio_chip *exar_gpio, *exar_temp;
> + int ret;
> + void __iomem *p;
> + int index = 1;

It looks better if you move int ret; to be a last in this block.

> +
> + if (idx != 0)
> + return 0;
> +
> + if (dev->vendor != PCI_VENDOR_ID_EXAR)
> + return 0;
> +
> + p = pci_ioremap_bar(dev, 0);
> + if (!p)
> + return -ENOMEM;
> +
> + exar_gpio = devm_kzalloc(&dev->dev, sizeof(*exar_gpio), GFP_KERNEL);
> + if (!exar_gpio) {
> + ret = -ENOMEM;
> + goto err_unmap;
> + }

You may do this before ioremap which makes less lines of code.

> +
> + mutex_init(&exar_gpio->lock);
> + INIT_LIST_HEAD(&exar_gpio->list);
> +
> + mutex_lock(&exar_mtx);
> + /* find the first unused index */
> + list_for_each_entry(exar_temp, &exar_list, list) {
> + if (exar_temp->index == index) {
> + index++;

> + continue;

Useless.

> + }
> + }
> +
> + sprintf(exar_gpio->name, "exar_gpio%d", index);
> + exar_gpio->gpio_chip.label = exar_gpio->name;
> + exar_gpio->gpio_chip.dev = &dev->dev;
> + exar_gpio->gpio_chip.direction_output = exar_direction_output;
> + exar_gpio->gpio_chip.direction_input = exar_direction_input;
> + exar_gpio->gpio_chip.get_direction = exar_get_direction;
> + exar_gpio->gpio_chip.get = exar_get_value;
> + exar_gpio->gpio_chip.set = exar_set_value;
> + exar_gpio->gpio_chip.base = -1;
> + exar_gpio->gpio_chip.ngpio = 16;

> + exar_gpio->gpio_chip.owner = THIS_MODULE;

Check if GPIO subsystem does that for you.

> + exar_gpio->regs = p;
> + exar_gpio->index = index;
> +
> + ret = gpiochip_add(&exar_gpio->gpio_chip);
> + if (ret)
> + goto err_destroy;
> +
> + exar_gpio->port = port;
> + port->port.private_data = exar_gpio;
> +
> + list_add_tail(&exar_gpio->list, &exar_list);
> + mutex_unlock(&exar_mtx);
> +
> + return 0;
> +
> +err_destroy:
> + mutex_unlock(&exar_mtx);
> + mutex_destroy(&exar_gpio->lock);
> +err_unmap:
> + iounmap(p);

pci_iounmap?

> + return ret;
> +}
> +EXPORT_SYMBOL(xr17v35x_gpio_init);
> +

> +static void __exit exar_gpio_exit(void)
> +{
> +}
> +
> +module_exit(exar_gpio_exit);
> +
> +static int __init exar_gpio_init(void)
> +{
> + return 0;
> +}
> +
> +module_init(exar_gpio_init);
> +

Useless for now. You are using it as a library.

> +MODULE_DESCRIPTION("Exar GPIO driver");
> +MODULE_AUTHOR("Sudip Mukherjee <sudipm.mukherjee@gmail.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
> index 4097f3f..2a73c47 100644
> --- a/drivers/tty/serial/8250/8250_pci.c
> +++ b/drivers/tty/serial/8250/8250_pci.c
> @@ -1764,12 +1764,20 @@ xr17v35x_has_slave(struct serial_private *priv)
> (dev_id == PCI_DEVICE_ID_EXAR_XR17V8358));
> }
>
> +static void pci_xr17v35x_exit(struct pci_dev *dev)
> +{
> + struct serial_private *priv = pci_get_drvdata(dev);
> +
> + xr17v35x_gpio_exit(serial8250_get_port(priv->line[0]));
> +}
> +
> static int
> pci_xr17v35x_setup(struct serial_private *priv,
> const struct pciserial_board *board,
> struct uart_8250_port *port, int idx)
> {
> u8 __iomem *p;
> + int ret;
>
> p = pci_ioremap_bar(priv->dev, 0);
> if (p == NULL)
> @@ -1807,7 +1815,11 @@ pci_xr17v35x_setup(struct serial_private *priv,
> writeb(128, p + UART_EXAR_RXTRG);
> iounmap(p);
>
> - return pci_default_setup(priv, board, port, idx);
> + ret = pci_default_setup(priv, board, port, idx);
> + if (ret)
> + return ret;
> +
> + return xr17v35x_gpio_init(priv->dev, port, idx);
> }
>
> #define PCI_DEVICE_ID_COMMTECH_4222PCI335 0x0004
> @@ -2407,6 +2419,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
> .subvendor = PCI_ANY_ID,
> .subdevice = PCI_ANY_ID,
> .setup = pci_xr17v35x_setup,
> + .exit = pci_xr17v35x_exit,
> },
> {
> .vendor = PCI_VENDOR_ID_EXAR,
> @@ -2414,6 +2427,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
> .subvendor = PCI_ANY_ID,
> .subdevice = PCI_ANY_ID,
> .setup = pci_xr17v35x_setup,
> + .exit = pci_xr17v35x_exit,
> },
> {
> .vendor = PCI_VENDOR_ID_EXAR,
> @@ -2421,6 +2435,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
> .subvendor = PCI_ANY_ID,
> .subdevice = PCI_ANY_ID,
> .setup = pci_xr17v35x_setup,
> + .exit = pci_xr17v35x_exit,
> },
> {
> .vendor = PCI_VENDOR_ID_EXAR,
> @@ -2428,6 +2443,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
> .subvendor = PCI_ANY_ID,
> .subdevice = PCI_ANY_ID,
> .setup = pci_xr17v35x_setup,
> + .exit = pci_xr17v35x_exit,
> },
> {
> .vendor = PCI_VENDOR_ID_EXAR,
> @@ -2435,6 +2451,7 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
> .subvendor = PCI_ANY_ID,
> .subdevice = PCI_ANY_ID,
> .setup = pci_xr17v35x_setup,
> + .exit = pci_xr17v35x_exit,
> },
> /*
> * Xircom cards
> diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> index b03cb517..852f1d2 100644
> --- a/drivers/tty/serial/8250/Kconfig
> +++ b/drivers/tty/serial/8250/Kconfig
> @@ -386,3 +386,11 @@ config SERIAL_OF_PLATFORM
> are probed through devicetree, including Open Firmware based
> PowerPC systems and embedded systems on architectures using the
> flattened device tree format.
> +
> +config SERIAL_8250_EXAR_GPIO
> + tristate "Support for GPIO pins on XR17V352/354/358"
> + depends on SERIAL_8250_PCI && GPIOLIB
> + select GPIO_SYSFS
> + help
> + Selecting this option will enable handling of GPIO pins present
> + on Exar XR17V352/354/358 chips.
> diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
> index 4ecb80d..bcf5f14 100644
> --- a/drivers/tty/serial/8250/Makefile
> +++ b/drivers/tty/serial/8250/Makefile
> @@ -29,5 +29,6 @@ obj-$(CONFIG_SERIAL_8250_UNIPHIER) += 8250_uniphier.o
> obj-$(CONFIG_SERIAL_8250_INGENIC) += 8250_ingenic.o
> obj-$(CONFIG_SERIAL_8250_MID) += 8250_mid.o
> obj-$(CONFIG_SERIAL_8250_OF) += 8250_of.o
> +obj-$(CONFIG_SERIAL_8250_EXAR_GPIO) += 8250_gpio.o
>
> CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt
> diff --git a/include/linux/8250_pci.h b/include/linux/8250_pci.h
> index b24ff08..803e55c 100644
> --- a/include/linux/8250_pci.h
> +++ b/include/linux/8250_pci.h
> @@ -35,3 +35,18 @@ pciserial_init_ports(struct pci_dev *dev, const struct pciserial_board *board);
> void pciserial_remove_ports(struct serial_private *priv);
> void pciserial_suspend_ports(struct serial_private *priv);
> void pciserial_resume_ports(struct serial_private *priv);
> +
> +struct uart_8250_port;

> +
> +#ifdef CONFIG_SERIAL_8250_EXAR_GPIO
> +int xr17v35x_gpio_init(struct pci_dev *, struct uart_8250_port *, int);
> +void xr17v35x_gpio_exit(struct uart_8250_port *);
> +#else /* CONFIG_SERIAL_8250_EXAR_GPIO */
> +static inline int xr17v35x_gpio_init(struct pci_dev *dev,
> + struct uart_8250_port *port, int idx)
> +{
> + return 0;
> +}
> +
> +static inline void xr17v35x_gpio_exit(struct uart_8250_port *port) { }
> +#endif /* CONFIG_SERIAL_8250_EXAR_GPIO */
> --
> 1.9.1
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/

--
With Best Regards,
Andy Shevchenko