1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Janz MODULbus VMOD-TTL GPIO Driver 4 * 5 * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu> 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/init.h> 11 #include <linux/interrupt.h> 12 #include <linux/delay.h> 13 #include <linux/platform_device.h> 14 #include <linux/io.h> 15 #include <linux/gpio/driver.h> 16 #include <linux/slab.h> 17 #include <linux/bitops.h> 18 19 #include <linux/mfd/janz.h> 20 21 #define DRV_NAME "janz-ttl" 22 23 #define PORTA_DIRECTION 0x23 24 #define PORTB_DIRECTION 0x2B 25 #define PORTC_DIRECTION 0x06 26 #define PORTA_IOCTL 0x24 27 #define PORTB_IOCTL 0x2C 28 #define PORTC_IOCTL 0x07 29 30 #define MASTER_INT_CTL 0x00 31 #define MASTER_CONF_CTL 0x01 32 33 #define CONF_PAE BIT(2) 34 #define CONF_PBE BIT(7) 35 #define CONF_PCE BIT(4) 36 37 struct ttl_control_regs { 38 __be16 portc; 39 __be16 portb; 40 __be16 porta; 41 __be16 control; 42 }; 43 44 struct ttl_module { 45 struct gpio_chip gpio; 46 47 /* base address of registers */ 48 struct ttl_control_regs __iomem *regs; 49 50 u8 portc_shadow; 51 u8 portb_shadow; 52 u8 porta_shadow; 53 54 spinlock_t lock; 55 }; 56 57 static int ttl_get_value(struct gpio_chip *gpio, unsigned offset) 58 { 59 struct ttl_module *mod = dev_get_drvdata(gpio->parent); 60 u8 *shadow; 61 int ret; 62 63 if (offset < 8) { 64 shadow = &mod->porta_shadow; 65 } else if (offset < 16) { 66 shadow = &mod->portb_shadow; 67 offset -= 8; 68 } else { 69 shadow = &mod->portc_shadow; 70 offset -= 16; 71 } 72 73 spin_lock(&mod->lock); 74 ret = *shadow & BIT(offset); 75 spin_unlock(&mod->lock); 76 return !!ret; 77 } 78 79 static void ttl_set_value(struct gpio_chip *gpio, unsigned offset, int value) 80 { 81 struct ttl_module *mod = dev_get_drvdata(gpio->parent); 82 void __iomem *port; 83 u8 *shadow; 84 85 if (offset < 8) { 86 port = &mod->regs->porta; 87 shadow = &mod->porta_shadow; 88 } else if (offset < 16) { 89 port = &mod->regs->portb; 90 shadow = &mod->portb_shadow; 91 offset -= 8; 92 } else { 93 port = &mod->regs->portc; 94 shadow = &mod->portc_shadow; 95 offset -= 16; 96 } 97 98 spin_lock(&mod->lock); 99 if (value) 100 *shadow |= BIT(offset); 101 else 102 *shadow &= ~BIT(offset); 103 104 iowrite16be(*shadow, port); 105 spin_unlock(&mod->lock); 106 } 107 108 static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val) 109 { 110 iowrite16be(reg, &mod->regs->control); 111 iowrite16be(val, &mod->regs->control); 112 } 113 114 static void ttl_setup_device(struct ttl_module *mod) 115 { 116 /* reset the device to a known state */ 117 iowrite16be(0x0000, &mod->regs->control); 118 iowrite16be(0x0001, &mod->regs->control); 119 iowrite16be(0x0000, &mod->regs->control); 120 121 /* put all ports in open-drain mode */ 122 ttl_write_reg(mod, PORTA_IOCTL, 0x00ff); 123 ttl_write_reg(mod, PORTB_IOCTL, 0x00ff); 124 ttl_write_reg(mod, PORTC_IOCTL, 0x000f); 125 126 /* set all ports as outputs */ 127 ttl_write_reg(mod, PORTA_DIRECTION, 0x0000); 128 ttl_write_reg(mod, PORTB_DIRECTION, 0x0000); 129 ttl_write_reg(mod, PORTC_DIRECTION, 0x0000); 130 131 /* set all ports to drive zeroes */ 132 iowrite16be(0x0000, &mod->regs->porta); 133 iowrite16be(0x0000, &mod->regs->portb); 134 iowrite16be(0x0000, &mod->regs->portc); 135 136 /* enable all ports */ 137 ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE); 138 } 139 140 static int ttl_probe(struct platform_device *pdev) 141 { 142 struct janz_platform_data *pdata; 143 struct device *dev = &pdev->dev; 144 struct ttl_module *mod; 145 struct gpio_chip *gpio; 146 int ret; 147 148 pdata = dev_get_platdata(&pdev->dev); 149 if (!pdata) { 150 dev_err(dev, "no platform data\n"); 151 return -ENXIO; 152 } 153 154 mod = devm_kzalloc(dev, sizeof(*mod), GFP_KERNEL); 155 if (!mod) 156 return -ENOMEM; 157 158 platform_set_drvdata(pdev, mod); 159 spin_lock_init(&mod->lock); 160 161 /* get access to the MODULbus registers for this module */ 162 mod->regs = devm_platform_ioremap_resource(pdev, 0); 163 if (IS_ERR(mod->regs)) 164 return PTR_ERR(mod->regs); 165 166 ttl_setup_device(mod); 167 168 /* Initialize the GPIO data structures */ 169 gpio = &mod->gpio; 170 gpio->parent = &pdev->dev; 171 gpio->label = pdev->name; 172 gpio->get = ttl_get_value; 173 gpio->set = ttl_set_value; 174 gpio->owner = THIS_MODULE; 175 176 /* request dynamic allocation */ 177 gpio->base = -1; 178 gpio->ngpio = 20; 179 180 ret = devm_gpiochip_add_data(dev, gpio, NULL); 181 if (ret) { 182 dev_err(dev, "unable to add GPIO chip\n"); 183 return ret; 184 } 185 186 return 0; 187 } 188 189 static struct platform_driver ttl_driver = { 190 .driver = { 191 .name = DRV_NAME, 192 }, 193 .probe = ttl_probe, 194 }; 195 196 module_platform_driver(ttl_driver); 197 198 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 199 MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver"); 200 MODULE_LICENSE("GPL"); 201 MODULE_ALIAS("platform:janz-ttl"); 202