1 // SPDX-License-Identifier: GPL-2.0-only 2 /* display7seg.c - Driver implementation for the 7-segment display 3 * present on Sun Microsystems CP1400 and CP1500 4 * 5 * Copyright (c) 2000 Eric Brower (ebrower@usa.net) 6 */ 7 8 #include <linux/device.h> 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/fs.h> 12 #include <linux/errno.h> 13 #include <linux/major.h> 14 #include <linux/miscdevice.h> 15 #include <linux/ioport.h> /* request_region */ 16 #include <linux/slab.h> 17 #include <linux/mutex.h> 18 #include <linux/of.h> 19 #include <linux/of_device.h> 20 #include <linux/atomic.h> 21 #include <linux/uaccess.h> /* put_/get_user */ 22 #include <asm/io.h> 23 24 #include <asm/display7seg.h> 25 26 #define DRIVER_NAME "d7s" 27 #define PFX DRIVER_NAME ": " 28 29 static DEFINE_MUTEX(d7s_mutex); 30 static int sol_compat = 0; /* Solaris compatibility mode */ 31 32 /* Solaris compatibility flag - 33 * The Solaris implementation omits support for several 34 * documented driver features (ref Sun doc 806-0180-03). 35 * By default, this module supports the documented driver 36 * abilities, rather than the Solaris implementation: 37 * 38 * 1) Device ALWAYS reverts to OBP-specified FLIPPED mode 39 * upon closure of device or module unload. 40 * 2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of 41 * FLIP bit 42 * 43 * If you wish the device to operate as under Solaris, 44 * omitting above features, set this parameter to non-zero. 45 */ 46 module_param(sol_compat, int, 0); 47 MODULE_PARM_DESC(sol_compat, 48 "Disables documented functionality omitted from Solaris driver"); 49 50 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>"); 51 MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500"); 52 MODULE_LICENSE("GPL"); 53 54 struct d7s { 55 void __iomem *regs; 56 bool flipped; 57 }; 58 struct d7s *d7s_device; 59 60 /* 61 * Register block address- see header for details 62 * ----------------------------------------- 63 * | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 | 64 * ----------------------------------------- 65 * 66 * DP - Toggles decimal point on/off 67 * ALARM - Toggles "Alarm" LED green/red 68 * FLIP - Inverts display for upside-down mounted board 69 * bits 0-4 - 7-segment display contents 70 */ 71 static atomic_t d7s_users = ATOMIC_INIT(0); 72 73 static int d7s_open(struct inode *inode, struct file *f) 74 { 75 if (D7S_MINOR != iminor(inode)) 76 return -ENODEV; 77 atomic_inc(&d7s_users); 78 return 0; 79 } 80 81 static int d7s_release(struct inode *inode, struct file *f) 82 { 83 /* Reset flipped state to OBP default only if 84 * no other users have the device open and we 85 * are not operating in solaris-compat mode 86 */ 87 if (atomic_dec_and_test(&d7s_users) && !sol_compat) { 88 struct d7s *p = d7s_device; 89 u8 regval = 0; 90 91 regval = readb(p->regs); 92 if (p->flipped) 93 regval |= D7S_FLIP; 94 else 95 regval &= ~D7S_FLIP; 96 writeb(regval, p->regs); 97 } 98 99 return 0; 100 } 101 102 static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 103 { 104 struct d7s *p = d7s_device; 105 u8 regs = readb(p->regs); 106 int error = 0; 107 u8 ireg = 0; 108 109 if (D7S_MINOR != iminor(file_inode(file))) 110 return -ENODEV; 111 112 mutex_lock(&d7s_mutex); 113 switch (cmd) { 114 case D7SIOCWR: 115 /* assign device register values we mask-out D7S_FLIP 116 * if in sol_compat mode 117 */ 118 if (get_user(ireg, (int __user *) arg)) { 119 error = -EFAULT; 120 break; 121 } 122 if (sol_compat) { 123 if (regs & D7S_FLIP) 124 ireg |= D7S_FLIP; 125 else 126 ireg &= ~D7S_FLIP; 127 } 128 writeb(ireg, p->regs); 129 break; 130 131 case D7SIOCRD: 132 /* retrieve device register values 133 * NOTE: Solaris implementation returns D7S_FLIP bit 134 * as toggled by user, even though it does not honor it. 135 * This driver will not misinform you about the state 136 * of your hardware while in sol_compat mode 137 */ 138 if (put_user(regs, (int __user *) arg)) { 139 error = -EFAULT; 140 break; 141 } 142 break; 143 144 case D7SIOCTM: 145 /* toggle device mode-- flip display orientation */ 146 regs ^= D7S_FLIP; 147 writeb(regs, p->regs); 148 break; 149 } 150 mutex_unlock(&d7s_mutex); 151 152 return error; 153 } 154 155 static const struct file_operations d7s_fops = { 156 .owner = THIS_MODULE, 157 .unlocked_ioctl = d7s_ioctl, 158 .compat_ioctl = compat_ptr_ioctl, 159 .open = d7s_open, 160 .release = d7s_release, 161 .llseek = noop_llseek, 162 }; 163 164 static struct miscdevice d7s_miscdev = { 165 .minor = D7S_MINOR, 166 .name = DRIVER_NAME, 167 .fops = &d7s_fops 168 }; 169 170 static int d7s_probe(struct platform_device *op) 171 { 172 struct device_node *opts; 173 int err = -EINVAL; 174 struct d7s *p; 175 u8 regs; 176 177 if (d7s_device) 178 goto out; 179 180 p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL); 181 err = -ENOMEM; 182 if (!p) 183 goto out; 184 185 p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s"); 186 if (!p->regs) { 187 printk(KERN_ERR PFX "Cannot map chip registers\n"); 188 goto out; 189 } 190 191 err = misc_register(&d7s_miscdev); 192 if (err) { 193 printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n", 194 D7S_MINOR); 195 goto out_iounmap; 196 } 197 198 /* OBP option "d7s-flipped?" is honored as default for the 199 * device, and reset default when detached 200 */ 201 regs = readb(p->regs); 202 opts = of_find_node_by_path("/options"); 203 if (opts && 204 of_get_property(opts, "d7s-flipped?", NULL)) 205 p->flipped = true; 206 207 if (p->flipped) 208 regs |= D7S_FLIP; 209 else 210 regs &= ~D7S_FLIP; 211 212 writeb(regs, p->regs); 213 214 printk(KERN_INFO PFX "7-Segment Display%pOF at [%s:0x%llx] %s\n", 215 op->dev.of_node, 216 (regs & D7S_FLIP) ? " (FLIPPED)" : "", 217 op->resource[0].start, 218 sol_compat ? "in sol_compat mode" : ""); 219 220 dev_set_drvdata(&op->dev, p); 221 d7s_device = p; 222 err = 0; 223 of_node_put(opts); 224 225 out: 226 return err; 227 228 out_iounmap: 229 of_iounmap(&op->resource[0], p->regs, sizeof(u8)); 230 goto out; 231 } 232 233 static int d7s_remove(struct platform_device *op) 234 { 235 struct d7s *p = dev_get_drvdata(&op->dev); 236 u8 regs = readb(p->regs); 237 238 /* Honor OBP d7s-flipped? unless operating in solaris-compat mode */ 239 if (sol_compat) { 240 if (p->flipped) 241 regs |= D7S_FLIP; 242 else 243 regs &= ~D7S_FLIP; 244 writeb(regs, p->regs); 245 } 246 247 misc_deregister(&d7s_miscdev); 248 of_iounmap(&op->resource[0], p->regs, sizeof(u8)); 249 250 return 0; 251 } 252 253 static const struct of_device_id d7s_match[] = { 254 { 255 .name = "display7seg", 256 }, 257 {}, 258 }; 259 MODULE_DEVICE_TABLE(of, d7s_match); 260 261 static struct platform_driver d7s_driver = { 262 .driver = { 263 .name = DRIVER_NAME, 264 .of_match_table = d7s_match, 265 }, 266 .probe = d7s_probe, 267 .remove = d7s_remove, 268 }; 269 270 module_platform_driver(d7s_driver); 271