drivers/gpio/gpio-zevio.c

   1 /*
   2  * GPIO controller in LSI ZEVIO SoCs.
   3  *
   4  * Author: Fabian Vogt <fabian@ritter-vogt.de>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/spinlock.h>
  12 #include <linux/errno.h>
  13 #include <linux/init.h>
  14 #include <linux/bitops.h>
  15 #include <linux/io.h>
  16 #include <linux/of_device.h>
  17 #include <linux/of_gpio.h>
  18 #include <linux/slab.h>
  19 #include <linux/gpio.h>
  20
  21 /*
  22  * Memory layout:
  23  * This chip has four gpio sections, each controls 8 GPIOs.
  24  * Bit 0 in section 0 is GPIO 0, bit 2 in section 1 is GPIO 10.
  25  * Disclaimer: Reverse engineered!
  26  * For more information refer to:
  27  * http://hackspire.unsads.com/wiki/index.php/Memory-mapped_I/O_ports#90000000_-_General_Purpose_I.2FO_.28GPIO.29
  28  *
  29  * 0x00-0x3F: Section 0
  30  *     +0x00: Masked interrupt status (read-only)
  31  *     +0x04: R: Interrupt status W: Reset interrupt status
  32  *     +0x08: R: Interrupt mask W: Mask interrupt
  33  *     +0x0C: W: Unmask interrupt (write-only)
  34  *     +0x10: Direction: I/O=1/0
  35  *     +0x14: Output
  36  *     +0x18: Input (read-only)
  37  *     +0x20: R: Level interrupt W: Set as level interrupt
  38  * 0x40-0x7F: Section 1
  39  * 0x80-0xBF: Section 2
  40  * 0xC0-0xFF: Section 3
  41  */
  42
  43 #define ZEVIO_GPIO_SECTION_SIZE                 0x40
  44
  45 /* Offsets to various registers */
  46 #define ZEVIO_GPIO_INT_MASKED_STATUS    0x00
  47 #define ZEVIO_GPIO_INT_STATUS           0x04
  48 #define ZEVIO_GPIO_INT_UNMASK           0x08
  49 #define ZEVIO_GPIO_INT_MASK             0x0C
  50 #define ZEVIO_GPIO_DIRECTION            0x10
  51 #define ZEVIO_GPIO_OUTPUT               0x14
  52 #define ZEVIO_GPIO_INPUT                        0x18
  53 #define ZEVIO_GPIO_INT_STICKY           0x20
  54
  55 /* Bit number of GPIO in its section */
  56 #define ZEVIO_GPIO_BIT(gpio) (gpio&7)
  57
  58 struct zevio_gpio {
  59         spinlock_t              lock;
  60         struct of_mm_gpio_chip  chip;
  61 };
  62
  63 static inline u32 zevio_gpio_port_get(struct zevio_gpio *c, unsigned pin,
  64                                         unsigned port_offset)
  65 {
  66         unsigned section_offset = ((pin >> 3) & 3)*ZEVIO_GPIO_SECTION_SIZE;
  67         return readl(IOMEM(c->chip.regs + section_offset + port_offset));
  68 }
  69
  70 static inline void zevio_gpio_port_set(struct zevio_gpio *c, unsigned pin,
  71                                         unsigned port_offset, u32 val)
  72 {
  73         unsigned section_offset = ((pin >> 3) & 3)*ZEVIO_GPIO_SECTION_SIZE;
  74         writel(val, IOMEM(c->chip.regs + section_offset + port_offset));
  75 }
  76
  77 /* Functions for struct gpio_chip */
  78 static int zevio_gpio_get(struct gpio_chip *chip, unsigned pin)
  79 {
  80         struct zevio_gpio *controller = gpiochip_get_data(chip);
  81         u32 val, dir;
  82
  83         spin_lock(&controller->lock);
  84         dir = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION);
  85         if (dir & BIT(ZEVIO_GPIO_BIT(pin)))
  86                 val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_INPUT);
  87         else
  88                 val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT);
  89         spin_unlock(&controller->lock);
  90
  91         return (val >> ZEVIO_GPIO_BIT(pin)) & 0x1;
  92 }
  93
  94 static void zevio_gpio_set(struct gpio_chip *chip, unsigned pin, int value)
  95 {
  96         struct zevio_gpio *controller = gpiochip_get_data(chip);
  97         u32 val;
  98
  99         spin_lock(&controller->lock);
 100         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT);
 101         if (value)
 102                 val |= BIT(ZEVIO_GPIO_BIT(pin));
 103         else
 104                 val &= ~BIT(ZEVIO_GPIO_BIT(pin));
 105
 106         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_OUTPUT, val);
 107         spin_unlock(&controller->lock);
 108 }
 109
 110 static int zevio_gpio_direction_input(struct gpio_chip *chip, unsigned pin)
 111 {
 112         struct zevio_gpio *controller = gpiochip_get_data(chip);
 113         u32 val;
 114
 115         spin_lock(&controller->lock);
 116
 117         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION);
 118         val |= BIT(ZEVIO_GPIO_BIT(pin));
 119         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_DIRECTION, val);
 120
 121         spin_unlock(&controller->lock);
 122
 123         return 0;
 124 }
 125
 126 static int zevio_gpio_direction_output(struct gpio_chip *chip,
 127                                        unsigned pin, int value)
 128 {
 129         struct zevio_gpio *controller = gpiochip_get_data(chip);
 130         u32 val;
 131
 132         spin_lock(&controller->lock);
 133         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT);
 134         if (value)
 135                 val |= BIT(ZEVIO_GPIO_BIT(pin));
 136         else
 137                 val &= ~BIT(ZEVIO_GPIO_BIT(pin));
 138
 139         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_OUTPUT, val);
 140         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION);
 141         val &= ~BIT(ZEVIO_GPIO_BIT(pin));
 142         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_DIRECTION, val);
 143
 144         spin_unlock(&controller->lock);
 145
 146         return 0;
 147 }
 148
 149 static int zevio_gpio_to_irq(struct gpio_chip *chip, unsigned pin)
 150 {
 151         /*
 152          * TODO: Implement IRQs.
 153          * Not implemented yet due to weird lockups
 154          */
 155
 156         return -ENXIO;
 157 }
 158
 159 static struct gpio_chip zevio_gpio_chip = {
 160         .direction_input        = zevio_gpio_direction_input,
 161         .direction_output       = zevio_gpio_direction_output,
 162         .set                    = zevio_gpio_set,
 163         .get                    = zevio_gpio_get,
 164         .to_irq                 = zevio_gpio_to_irq,
 165         .base                   = 0,
 166         .owner                  = THIS_MODULE,
 167         .ngpio                  = 32,
 168         .of_gpio_n_cells        = 2,
 169 };
 170
 171 /* Initialization */
 172 static int zevio_gpio_probe(struct platform_device *pdev)
 173 {
 174         struct zevio_gpio *controller;
 175         int status, i;
 176
 177         controller = devm_kzalloc(&pdev->dev, sizeof(*controller), GFP_KERNEL);
 178         if (!controller)
 179                 return -ENOMEM;
 180
 181         platform_set_drvdata(pdev, controller);
 182
 183         /* Copy our reference */
 184         controller->chip.gc = zevio_gpio_chip;
 185         controller->chip.gc.parent = &pdev->dev;
 186
 187         status = of_mm_gpiochip_add_data(pdev->dev.of_node,
 188                                          &(controller->chip),
 189                                          controller);
 190         if (status) {
 191                 dev_err(&pdev->dev, "failed to add gpiochip: %d\n", status);
 192                 return status;
 193         }
 194
 195         spin_lock_init(&controller->lock);
 196
 197         /* Disable interrupts, they only cause errors */
 198         for (i = 0; i < controller->chip.gc.ngpio; i += 8)
 199                 zevio_gpio_port_set(controller, i, ZEVIO_GPIO_INT_MASK, 0xFF);
 200
 201         dev_dbg(controller->chip.gc.parent, "ZEVIO GPIO controller set up!\n");
 202
 203         return 0;
 204 }
 205
 206 static const struct of_device_id zevio_gpio_of_match[] = {
 207         { .compatible = "lsi,zevio-gpio", },
 208         { },
 209 };
 210
 211 static struct platform_driver zevio_gpio_driver = {
 212         .driver         = {
 213                 .name   = "gpio-zevio",
 214                 .of_match_table = zevio_gpio_of_match,
 215                 .suppress_bind_attrs = true,
 216         },
 217         .probe          = zevio_gpio_probe,
 218 };
 219 builtin_platform_driver(zevio_gpio_driver);