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"); 208