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1// SPDX-License-Identifier: GPL-2.02/*3 * Intel 8255 Programmable Peripheral Interface4 * Copyright (C) 2022 William Breathitt Gray5 */6#include <linux/bits.h>7#include <linux/device.h>8#include <linux/err.h>9#include <linux/export.h>10#include <linux/gpio/regmap.h>11#include <linux/module.h>12#include <linux/regmap.h>13 14#include "gpio-i8255.h"15 16#define I8255_NGPIO 2417#define I8255_NGPIO_PER_REG 818#define I8255_CONTROL_PORTC_LOWER_DIRECTION BIT(0)19#define I8255_CONTROL_PORTB_DIRECTION BIT(1)20#define I8255_CONTROL_PORTC_UPPER_DIRECTION BIT(3)21#define I8255_CONTROL_PORTA_DIRECTION BIT(4)22#define I8255_CONTROL_MODE_SET BIT(7)23#define I8255_PORTA 0x024#define I8255_PORTB 0x125#define I8255_PORTC 0x226#define I8255_CONTROL 0x327#define I8255_REG_DAT_BASE I8255_PORTA28#define I8255_REG_DIR_IN_BASE I8255_CONTROL29 30static int i8255_direction_mask(const unsigned int offset)31{32 const unsigned int stride = offset / I8255_NGPIO_PER_REG;33 const unsigned int line = offset % I8255_NGPIO_PER_REG;34 35 switch (stride) {36 case I8255_PORTA:37 return I8255_CONTROL_PORTA_DIRECTION;38 case I8255_PORTB:39 return I8255_CONTROL_PORTB_DIRECTION;40 case I8255_PORTC:41 /* Port C can be configured by nibble */42 if (line >= 4)43 return I8255_CONTROL_PORTC_UPPER_DIRECTION;44 return I8255_CONTROL_PORTC_LOWER_DIRECTION;45 default:46 /* Should never reach this path */47 return 0;48 }49}50 51static int i8255_ppi_init(struct regmap *const map, const unsigned int base)52{53 int err;54 55 /* Configure all ports to MODE 0 output mode */56 err = regmap_write(map, base + I8255_CONTROL, I8255_CONTROL_MODE_SET);57 if (err)58 return err;59 60 /* Initialize all GPIO to output 0 */61 err = regmap_write(map, base + I8255_PORTA, 0x00);62 if (err)63 return err;64 err = regmap_write(map, base + I8255_PORTB, 0x00);65 if (err)66 return err;67 return regmap_write(map, base + I8255_PORTC, 0x00);68}69 70static int i8255_reg_mask_xlate(struct gpio_regmap *gpio, unsigned int base,71 unsigned int offset, unsigned int *reg,72 unsigned int *mask)73{74 const unsigned int ppi = offset / I8255_NGPIO;75 const unsigned int ppi_offset = offset % I8255_NGPIO;76 const unsigned int stride = ppi_offset / I8255_NGPIO_PER_REG;77 const unsigned int line = ppi_offset % I8255_NGPIO_PER_REG;78 79 switch (base) {80 case I8255_REG_DAT_BASE:81 *reg = base + stride + ppi * 4;82 *mask = BIT(line);83 return 0;84 case I8255_REG_DIR_IN_BASE:85 *reg = base + ppi * 4;86 *mask = i8255_direction_mask(ppi_offset);87 return 0;88 default:89 /* Should never reach this path */90 return -EINVAL;91 }92}93 94/**95 * devm_i8255_regmap_register - Register an i8255 GPIO controller96 * @dev: device that is registering this i8255 GPIO device97 * @config: configuration for i8255_regmap_config98 *99 * Registers an Intel 8255 Programmable Peripheral Interface GPIO controller.100 * Returns 0 on success and negative error number on failure.101 */102int devm_i8255_regmap_register(struct device *const dev,103 const struct i8255_regmap_config *const config)104{105 struct gpio_regmap_config gpio_config = {0};106 unsigned long i;107 int err;108 109 if (!config->parent)110 return -EINVAL;111 112 if (!config->map)113 return -EINVAL;114 115 if (!config->num_ppi)116 return -EINVAL;117 118 for (i = 0; i < config->num_ppi; i++) {119 err = i8255_ppi_init(config->map, i * 4);120 if (err)121 return err;122 }123 124 gpio_config.parent = config->parent;125 gpio_config.regmap = config->map;126 gpio_config.ngpio = I8255_NGPIO * config->num_ppi;127 gpio_config.names = config->names;128 gpio_config.reg_dat_base = GPIO_REGMAP_ADDR(I8255_REG_DAT_BASE);129 gpio_config.reg_set_base = GPIO_REGMAP_ADDR(I8255_REG_DAT_BASE);130 gpio_config.reg_dir_in_base = GPIO_REGMAP_ADDR(I8255_REG_DIR_IN_BASE);131 gpio_config.ngpio_per_reg = I8255_NGPIO_PER_REG;132 gpio_config.irq_domain = config->domain;133 gpio_config.reg_mask_xlate = i8255_reg_mask_xlate;134 135 return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));136}137EXPORT_SYMBOL_NS_GPL(devm_i8255_regmap_register, I8255);138 139MODULE_AUTHOR("William Breathitt Gray");140MODULE_DESCRIPTION("Intel 8255 Programmable Peripheral Interface");141MODULE_LICENSE("GPL");142