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 int ttl_set_value(struct gpio_chip *gpio, unsigned int 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 return 0; 108 } 109 110 static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val) 111 { 112 iowrite16be(reg, &mod->regs->control); 113 iowrite16be(val, &mod->regs->control); 114 } 115 116 static void ttl_setup_device(struct ttl_module *mod) 117 { 118 /* reset the device to a known state */ 119 iowrite16be(0x0000, &mod->regs->control); 120 iowrite16be(0x0001, &mod->regs->control); 121 iowrite16be(0x0000, &mod->regs->control); 122 123 /* put all ports in open-drain mode */ 124 ttl_write_reg(mod, PORTA_IOCTL, 0x00ff); 125 ttl_write_reg(mod, PORTB_IOCTL, 0x00ff); 126 ttl_write_reg(mod, PORTC_IOCTL, 0x000f); 127 128 /* set all ports as outputs */ 129 ttl_write_reg(mod, PORTA_DIRECTION, 0x0000); 130 ttl_write_reg(mod, PORTB_DIRECTION, 0x0000); 131 ttl_write_reg(mod, PORTC_DIRECTION, 0x0000); 132 133 /* set all ports to drive zeroes */ 134 iowrite16be(0x0000, &mod->regs->porta); 135 iowrite16be(0x0000, &mod->regs->portb); 136 iowrite16be(0x0000, &mod->regs->portc); 137 138 /* enable all ports */ 139 ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE); 140 } 141 142 static int ttl_probe(struct platform_device *pdev) 143 { 144 struct janz_platform_data *pdata; 145 struct ttl_module *mod; 146 struct gpio_chip *gpio; 147 int ret; 148 149 pdata = dev_get_platdata(&pdev->dev); 150 if (!pdata) { 151 dev_err(&pdev->dev, "no platform data\n"); 152 return -ENXIO; 153 } 154 155 mod = devm_kzalloc(&pdev->dev, sizeof(*mod), GFP_KERNEL); 156 if (!mod) 157 return -ENOMEM; 158 159 platform_set_drvdata(pdev, mod); 160 spin_lock_init(&mod->lock); 161 162 /* get access to the MODULbus registers for this module */ 163 mod->regs = devm_platform_ioremap_resource(pdev, 0); 164 if (IS_ERR(mod->regs)) 165 return PTR_ERR(mod->regs); 166 167 ttl_setup_device(mod); 168 169 /* Initialize the GPIO data structures */ 170 gpio = &mod->gpio; 171 gpio->parent = &pdev->dev; 172 gpio->label = pdev->name; 173 gpio->get = ttl_get_value; 174 gpio->set = ttl_set_value; 175 gpio->owner = THIS_MODULE; 176 177 /* request dynamic allocation */ 178 gpio->base = -1; 179 gpio->ngpio = 20; 180 181 ret = devm_gpiochip_add_data(&pdev->dev, gpio, NULL); 182 if (ret) { 183 dev_err(&pdev->dev, "unable to add GPIO chip\n"); 184 return ret; 185 } 186 187 return 0; 188 } 189 190 static struct platform_driver ttl_driver = { 191 .driver = { 192 .name = DRV_NAME, 193 }, 194 .probe = ttl_probe, 195 }; 196 197 module_platform_driver(ttl_driver); 198 199 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); 200 MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver"); 201 MODULE_LICENSE("GPL"); 202 MODULE_ALIAS("platform:janz-ttl"); 203