drivers/gpio/gpio-janz-ttl.c

   1 /*
   2  * Janz MODULbus VMOD-TTL GPIO Driver
   3  *
   4  * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2 of the License, or (at your
   9  * option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/delay.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/io.h>
  19 #include <linux/gpio.h>
  20 #include <linux/slab.h>
  21
  22 #include <linux/mfd/janz.h>
  23
  24 #define DRV_NAME "janz-ttl"
  25
  26 #define PORTA_DIRECTION         0x23
  27 #define PORTB_DIRECTION         0x2B
  28 #define PORTC_DIRECTION         0x06
  29 #define PORTA_IOCTL             0x24
  30 #define PORTB_IOCTL             0x2C
  31 #define PORTC_IOCTL             0x07
  32
  33 #define MASTER_INT_CTL          0x00
  34 #define MASTER_CONF_CTL         0x01
  35
  36 #define CONF_PAE                (1 << 2)
  37 #define CONF_PBE                (1 << 7)
  38 #define CONF_PCE                (1 << 4)
  39
  40 struct ttl_control_regs {
  41         __be16 portc;
  42         __be16 portb;
  43         __be16 porta;
  44         __be16 control;
  45 };
  46
  47 struct ttl_module {
  48         struct gpio_chip gpio;
  49
  50         /* base address of registers */
  51         struct ttl_control_regs __iomem *regs;
  52
  53         u8 portc_shadow;
  54         u8 portb_shadow;
  55         u8 porta_shadow;
  56
  57         spinlock_t lock;
  58 };
  59
  60 static int ttl_get_value(struct gpio_chip *gpio, unsigned offset)
  61 {
  62         struct ttl_module *mod = dev_get_drvdata(gpio->dev);
  63         u8 *shadow;
  64         int ret;
  65
  66         if (offset < 8) {
  67                 shadow = &mod->porta_shadow;
  68         } else if (offset < 16) {
  69                 shadow = &mod->portb_shadow;
  70                 offset -= 8;
  71         } else {
  72                 shadow = &mod->portc_shadow;
  73                 offset -= 16;
  74         }
  75
  76         spin_lock(&mod->lock);
  77         ret = *shadow & (1 << offset);
  78         spin_unlock(&mod->lock);
  79         return ret;
  80 }
  81
  82 static void ttl_set_value(struct gpio_chip *gpio, unsigned offset, int value)
  83 {
  84         struct ttl_module *mod = dev_get_drvdata(gpio->dev);
  85         void __iomem *port;
  86         u8 *shadow;
  87
  88         if (offset < 8) {
  89                 port = &mod->regs->porta;
  90                 shadow = &mod->porta_shadow;
  91         } else if (offset < 16) {
  92                 port = &mod->regs->portb;
  93                 shadow = &mod->portb_shadow;
  94                 offset -= 8;
  95         } else {
  96                 port = &mod->regs->portc;
  97                 shadow = &mod->portc_shadow;
  98                 offset -= 16;
  99         }
 100
 101         spin_lock(&mod->lock);
 102         if (value)
 103                 *shadow |= (1 << offset);
 104         else
 105                 *shadow &= ~(1 << offset);
 106
 107         iowrite16be(*shadow, port);
 108         spin_unlock(&mod->lock);
 109 }
 110
 111 static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val)
 112 {
 113         iowrite16be(reg, &mod->regs->control);
 114         iowrite16be(val, &mod->regs->control);
 115 }
 116
 117 static void ttl_setup_device(struct ttl_module *mod)
 118 {
 119         /* reset the device to a known state */
 120         iowrite16be(0x0000, &mod->regs->control);
 121         iowrite16be(0x0001, &mod->regs->control);
 122         iowrite16be(0x0000, &mod->regs->control);
 123
 124         /* put all ports in open-drain mode */
 125         ttl_write_reg(mod, PORTA_IOCTL, 0x00ff);
 126         ttl_write_reg(mod, PORTB_IOCTL, 0x00ff);
 127         ttl_write_reg(mod, PORTC_IOCTL, 0x000f);
 128
 129         /* set all ports as outputs */
 130         ttl_write_reg(mod, PORTA_DIRECTION, 0x0000);
 131         ttl_write_reg(mod, PORTB_DIRECTION, 0x0000);
 132         ttl_write_reg(mod, PORTC_DIRECTION, 0x0000);
 133
 134         /* set all ports to drive zeroes */
 135         iowrite16be(0x0000, &mod->regs->porta);
 136         iowrite16be(0x0000, &mod->regs->portb);
 137         iowrite16be(0x0000, &mod->regs->portc);
 138
 139         /* enable all ports */
 140         ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE);
 141 }
 142
 143 static int ttl_probe(struct platform_device *pdev)
 144 {
 145         struct janz_platform_data *pdata;
 146         struct device *dev = &pdev->dev;
 147         struct ttl_module *mod;
 148         struct gpio_chip *gpio;
 149         struct resource *res;
 150         int ret;
 151
 152         pdata = dev_get_platdata(&pdev->dev);
 153         if (!pdata) {
 154                 dev_err(dev, "no platform data\n");
 155                 return -ENXIO;
 156         }
 157
 158         mod = devm_kzalloc(dev, sizeof(*mod), GFP_KERNEL);
 159         if (!mod)
 160                 return -ENOMEM;
 161
 162         platform_set_drvdata(pdev, mod);
 163         spin_lock_init(&mod->lock);
 164
 165         /* get access to the MODULbus registers for this module */
 166         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 167         mod->regs = devm_ioremap_resource(dev, res);
 168         if (IS_ERR(mod->regs))
 169                 return PTR_ERR(mod->regs);
 170
 171         ttl_setup_device(mod);
 172
 173         /* Initialize the GPIO data structures */
 174         gpio = &mod->gpio;
 175         gpio->dev = &pdev->dev;
 176         gpio->label = pdev->name;
 177         gpio->get = ttl_get_value;
 178         gpio->set = ttl_set_value;
 179         gpio->owner = THIS_MODULE;
 180
 181         /* request dynamic allocation */
 182         gpio->base = -1;
 183         gpio->ngpio = 20;
 184
 185         ret = gpiochip_add(gpio);
 186         if (ret) {
 187                 dev_err(dev, "unable to add GPIO chip\n");
 188                 return ret;
 189         }
 190
 191         return 0;
 192 }
 193
 194 static int ttl_remove(struct platform_device *pdev)
 195 {
 196         struct ttl_module *mod = platform_get_drvdata(pdev);
 197
 198         gpiochip_remove(&mod->gpio);
 199
 200         return 0;
 201 }
 202
 203 static struct platform_driver ttl_driver = {
 204         .driver         = {
 205                 .name   = DRV_NAME,
 206         },
 207         .probe          = ttl_probe,
 208         .remove         = ttl_remove,
 209 };
 210
 211 module_platform_driver(ttl_driver);
 212
 213 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 214 MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver");
 215 MODULE_LICENSE("GPL");
 216 MODULE_ALIAS("platform:janz-ttl");