![Jan Kiszka](/assets/img/avatar_default.png)
On the SIMATIC, IOT2040 only a single pin is exportable as GPIO, the rest is required to operate the UART. To allow modeling this case, expand the platform device data structure to specify a (consecutive) pin subset for exporting by the gpio-exar driver. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
205 lines
5.4 KiB
C
205 lines
5.4 KiB
C
/*
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* GPIO driver for Exar XR17V35X chip
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*
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* Copyright (C) 2015 Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/bitops.h>
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#include <linux/device.h>
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#include <linux/gpio/driver.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/platform_device.h>
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#define EXAR_OFFSET_MPIOLVL_LO 0x90
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#define EXAR_OFFSET_MPIOSEL_LO 0x93
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#define EXAR_OFFSET_MPIOLVL_HI 0x96
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#define EXAR_OFFSET_MPIOSEL_HI 0x99
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#define DRIVER_NAME "gpio_exar"
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static DEFINE_IDA(ida_index);
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struct exar_gpio_chip {
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struct gpio_chip gpio_chip;
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struct mutex lock;
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int index;
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void __iomem *regs;
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char name[20];
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unsigned int first_pin;
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};
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static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
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unsigned int offset)
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{
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struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
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int temp;
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mutex_lock(&exar_gpio->lock);
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temp = readb(exar_gpio->regs + reg);
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temp &= ~BIT(offset);
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if (val)
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temp |= BIT(offset);
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writeb(temp, exar_gpio->regs + reg);
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mutex_unlock(&exar_gpio->lock);
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}
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static int exar_set_direction(struct gpio_chip *chip, int direction,
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unsigned int offset)
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{
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struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
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unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
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EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
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unsigned int bit = (offset + exar_gpio->first_pin) % 8;
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exar_update(chip, addr, direction, bit);
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return 0;
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}
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static int exar_get(struct gpio_chip *chip, unsigned int reg)
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{
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struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
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int value;
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mutex_lock(&exar_gpio->lock);
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value = readb(exar_gpio->regs + reg);
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mutex_unlock(&exar_gpio->lock);
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return value;
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}
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static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
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{
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struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
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unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
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EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
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unsigned int bit = (offset + exar_gpio->first_pin) % 8;
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return !!(exar_get(chip, addr) & BIT(bit));
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}
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static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
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{
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struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
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unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
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EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
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unsigned int bit = (offset + exar_gpio->first_pin) % 8;
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return !!(exar_get(chip, addr) & BIT(bit));
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}
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static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
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int value)
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{
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struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
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unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
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EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
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unsigned int bit = (offset + exar_gpio->first_pin) % 8;
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exar_update(chip, addr, value, bit);
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}
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static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
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int value)
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{
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exar_set_value(chip, offset, value);
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return exar_set_direction(chip, 0, offset);
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}
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static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
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{
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return exar_set_direction(chip, 1, offset);
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}
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static int gpio_exar_probe(struct platform_device *pdev)
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{
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struct pci_dev *pcidev = to_pci_dev(pdev->dev.parent);
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struct exar_gpio_chip *exar_gpio;
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u32 first_pin, ngpios;
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void __iomem *p;
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int index, ret;
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/*
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* The UART driver must have mapped region 0 prior to registering this
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* device - use it.
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*/
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p = pcim_iomap_table(pcidev)[0];
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if (!p)
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return -ENOMEM;
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ret = device_property_read_u32(&pdev->dev, "linux,first-pin",
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&first_pin);
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if (ret)
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return ret;
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ret = device_property_read_u32(&pdev->dev, "ngpios", &ngpios);
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if (ret)
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return ret;
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exar_gpio = devm_kzalloc(&pdev->dev, sizeof(*exar_gpio), GFP_KERNEL);
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if (!exar_gpio)
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return -ENOMEM;
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mutex_init(&exar_gpio->lock);
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index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
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sprintf(exar_gpio->name, "exar_gpio%d", index);
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exar_gpio->gpio_chip.label = exar_gpio->name;
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exar_gpio->gpio_chip.parent = &pdev->dev;
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exar_gpio->gpio_chip.direction_output = exar_direction_output;
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exar_gpio->gpio_chip.direction_input = exar_direction_input;
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exar_gpio->gpio_chip.get_direction = exar_get_direction;
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exar_gpio->gpio_chip.get = exar_get_value;
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exar_gpio->gpio_chip.set = exar_set_value;
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exar_gpio->gpio_chip.base = -1;
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exar_gpio->gpio_chip.ngpio = ngpios;
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exar_gpio->regs = p;
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exar_gpio->index = index;
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exar_gpio->first_pin = first_pin;
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ret = devm_gpiochip_add_data(&pdev->dev,
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&exar_gpio->gpio_chip, exar_gpio);
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if (ret)
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goto err_destroy;
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platform_set_drvdata(pdev, exar_gpio);
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return 0;
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err_destroy:
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ida_simple_remove(&ida_index, index);
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mutex_destroy(&exar_gpio->lock);
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return ret;
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}
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static int gpio_exar_remove(struct platform_device *pdev)
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{
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struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
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ida_simple_remove(&ida_index, exar_gpio->index);
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mutex_destroy(&exar_gpio->lock);
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return 0;
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}
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static struct platform_driver gpio_exar_driver = {
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.probe = gpio_exar_probe,
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.remove = gpio_exar_remove,
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.driver = {
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.name = DRIVER_NAME,
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},
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};
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module_platform_driver(gpio_exar_driver);
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MODULE_ALIAS("platform:" DRIVER_NAME);
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MODULE_DESCRIPTION("Exar GPIO driver");
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MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
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MODULE_LICENSE("GPL");
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