1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Intel 8255 Programmable Peripheral Interface
4 * Copyright (C) 2022 William Breathitt Gray
5 */
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 24
17 #define I8255_NGPIO_PER_REG 8
18 #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 0x0
24 #define I8255_PORTB 0x1
25 #define I8255_PORTC 0x2
26 #define I8255_CONTROL 0x3
27 #define I8255_REG_DAT_BASE I8255_PORTA
28 #define I8255_REG_DIR_IN_BASE I8255_CONTROL
29
i8255_direction_mask(const unsigned int offset)30 static 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
i8255_ppi_init(struct regmap * const map,const unsigned int base)51 static 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
i8255_reg_mask_xlate(struct gpio_regmap * gpio,unsigned int base,unsigned int offset,unsigned int * reg,unsigned int * mask)70 static 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 controller
96 * @dev: device that is registering this i8255 GPIO device
97 * @config: configuration for i8255_regmap_config
98 *
99 * Registers an Intel 8255 Programmable Peripheral Interface GPIO controller.
100 * Returns 0 on success and negative error number on failure.
101 */
devm_i8255_regmap_register(struct device * const dev,const struct i8255_regmap_config * const config)102 int 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 }
137 EXPORT_SYMBOL_NS_GPL(devm_i8255_regmap_register, "I8255");
138
139 MODULE_AUTHOR("William Breathitt Gray");
140 MODULE_DESCRIPTION("Intel 8255 Programmable Peripheral Interface");
141 MODULE_LICENSE("GPL");
142