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/module.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 #define to_zevio_gpio(chip) container_of(to_of_mm_gpio_chip(chip), \
  56                                 struct zevio_gpio, chip)
  57
  58 /* Bit number of GPIO in its section */
  59 #define ZEVIO_GPIO_BIT(gpio) (gpio&7)
  60
  61 struct zevio_gpio {
  62         spinlock_t              lock;
  63         struct of_mm_gpio_chip  chip;
  64 };
  65
  66 static inline u32 zevio_gpio_port_get(struct zevio_gpio *c, unsigned pin,
  67                                         unsigned port_offset)
  68 {
  69         unsigned section_offset = ((pin >> 3) & 3)*ZEVIO_GPIO_SECTION_SIZE;
  70         return readl(IOMEM(c->chip.regs + section_offset + port_offset));
  71 }
  72
  73 static inline void zevio_gpio_port_set(struct zevio_gpio *c, unsigned pin,
  74                                         unsigned port_offset, u32 val)
  75 {
  76         unsigned section_offset = ((pin >> 3) & 3)*ZEVIO_GPIO_SECTION_SIZE;
  77         writel(val, IOMEM(c->chip.regs + section_offset + port_offset));
  78 }
  79
  80 /* Functions for struct gpio_chip */
  81 static int zevio_gpio_get(struct gpio_chip *chip, unsigned pin)
  82 {
  83         struct zevio_gpio *controller = to_zevio_gpio(chip);
  84
  85         /* Only reading allowed, so no spinlock needed */
  86         u32 val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_INPUT);
  87
  88         return (val >> ZEVIO_GPIO_BIT(pin)) & 0x1;
  89 }
  90
  91 static void zevio_gpio_set(struct gpio_chip *chip, unsigned pin, int value)
  92 {
  93         struct zevio_gpio *controller = to_zevio_gpio(chip);
  94         u32 val;
  95
  96         spin_lock(&controller->lock);
  97         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT);
  98         if (value)
  99                 val |= BIT(ZEVIO_GPIO_BIT(pin));
 100         else
 101                 val &= ~BIT(ZEVIO_GPIO_BIT(pin));
 102
 103         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_OUTPUT, val);
 104         spin_unlock(&controller->lock);
 105 }
 106
 107 static int zevio_gpio_direction_input(struct gpio_chip *chip, unsigned pin)
 108 {
 109         struct zevio_gpio *controller = to_zevio_gpio(chip);
 110         u32 val;
 111
 112         spin_lock(&controller->lock);
 113
 114         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION);
 115         val |= BIT(ZEVIO_GPIO_BIT(pin));
 116         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_DIRECTION, val);
 117
 118         spin_unlock(&controller->lock);
 119
 120         return 0;
 121 }
 122
 123 static int zevio_gpio_direction_output(struct gpio_chip *chip,
 124                                        unsigned pin, int value)
 125 {
 126         struct zevio_gpio *controller = to_zevio_gpio(chip);
 127         u32 val;
 128
 129         spin_lock(&controller->lock);
 130         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT);
 131         if (value)
 132                 val |= BIT(ZEVIO_GPIO_BIT(pin));
 133         else
 134                 val &= ~BIT(ZEVIO_GPIO_BIT(pin));
 135
 136         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_OUTPUT, val);
 137         val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION);
 138         val &= ~BIT(ZEVIO_GPIO_BIT(pin));
 139         zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_DIRECTION, val);
 140
 141         spin_unlock(&controller->lock);
 142
 143         return 0;
 144 }
 145
 146 static int zevio_gpio_to_irq(struct gpio_chip *chip, unsigned pin)
 147 {
 148         /*
 149          * TODO: Implement IRQs.
 150          * Not implemented yet due to weird lockups
 151          */
 152
 153         return -ENXIO;
 154 }
 155
 156 static struct gpio_chip zevio_gpio_chip = {
 157         .direction_input        = zevio_gpio_direction_input,
 158         .direction_output       = zevio_gpio_direction_output,
 159         .set                    = zevio_gpio_set,
 160         .get                    = zevio_gpio_get,
 161         .to_irq                 = zevio_gpio_to_irq,
 162         .base                   = 0,
 163         .owner                  = THIS_MODULE,
 164         .ngpio                  = 32,
 165         .of_gpio_n_cells        = 2,
 166 };
 167
 168 /* Initialization */
 169 static int zevio_gpio_probe(struct platform_device *pdev)
 170 {
 171         struct zevio_gpio *controller;
 172         int status, i;
 173
 174         controller = devm_kzalloc(&pdev->dev, sizeof(*controller), GFP_KERNEL);
 175         if (!controller) {
 176                 dev_err(&pdev->dev, "not enough free memory\n");
 177                 return -ENOMEM;
 178         }
 179
 180         /* Copy our reference */
 181         controller->chip.gc = zevio_gpio_chip;
 182         controller->chip.gc.dev = &pdev->dev;
 183
 184         status = of_mm_gpiochip_add(pdev->dev.of_node, &(controller->chip));
 185         if (status) {
 186                 dev_err(&pdev->dev, "failed to add gpiochip: %d\n", status);
 187                 return status;
 188         }
 189
 190         spin_lock_init(&controller->lock);
 191
 192         /* Disable interrupts, they only cause errors */
 193         for (i = 0; i < controller->chip.gc.ngpio; i += 8)
 194                 zevio_gpio_port_set(controller, i, ZEVIO_GPIO_INT_MASK, 0xFF);
 195
 196         dev_dbg(controller->chip.gc.dev, "ZEVIO GPIO controller set up!\n");
 197
 198         return 0;
 199 }
 200
 201 static struct of_device_id zevio_gpio_of_match[] = {
 202         { .compatible = "lsi,zevio-gpio", },
 203         { },
 204 };
 205
 206 MODULE_DEVICE_TABLE(of, zevio_gpio_of_match);
 207
 208 static struct platform_driver zevio_gpio_driver = {
 209         .driver         = {
 210                 .name   = "gpio-zevio",
 211                 .owner  = THIS_MODULE,
 212                 .of_match_table = of_match_ptr(zevio_gpio_of_match),
 213         },
 214         .probe          = zevio_gpio_probe,
 215 };
 216 module_platform_driver(zevio_gpio_driver);
 217
 218 MODULE_LICENSE("GPL");
 219 MODULE_AUTHOR("Fabian Vogt <fabian@ritter-vogt.de>");
 220 MODULE_DESCRIPTION("LSI ZEVIO SoC GPIO driver");