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