diff options
Diffstat (limited to 'drivers/sbus/char/display7seg.c')
| -rw-r--r-- | drivers/sbus/char/display7seg.c | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/drivers/sbus/char/display7seg.c b/drivers/sbus/char/display7seg.c new file mode 100644 index 000000000..d93595b39 --- /dev/null +++ b/drivers/sbus/char/display7seg.c @@ -0,0 +1,270 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* display7seg.c - Driver implementation for the 7-segment display + * present on Sun Microsystems CP1400 and CP1500 + * + * Copyright (c) 2000 Eric Brower (ebrower@usa.net) + */ + +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/errno.h> +#include <linux/major.h> +#include <linux/miscdevice.h> +#include <linux/ioport.h> /* request_region */ +#include <linux/slab.h> +#include <linux/mutex.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/atomic.h> +#include <linux/uaccess.h> /* put_/get_user */ +#include <asm/io.h> + +#include <asm/display7seg.h> + +#define DRIVER_NAME "d7s" +#define PFX DRIVER_NAME ": " + +static DEFINE_MUTEX(d7s_mutex); +static int sol_compat = 0; /* Solaris compatibility mode */ + +/* Solaris compatibility flag - + * The Solaris implementation omits support for several + * documented driver features (ref Sun doc 806-0180-03). + * By default, this module supports the documented driver + * abilities, rather than the Solaris implementation: + * + * 1) Device ALWAYS reverts to OBP-specified FLIPPED mode + * upon closure of device or module unload. + * 2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of + * FLIP bit + * + * If you wish the device to operate as under Solaris, + * omitting above features, set this parameter to non-zero. + */ +module_param(sol_compat, int, 0); +MODULE_PARM_DESC(sol_compat, + "Disables documented functionality omitted from Solaris driver"); + +MODULE_AUTHOR("Eric Brower <ebrower@usa.net>"); +MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500"); +MODULE_LICENSE("GPL"); + +struct d7s { + void __iomem *regs; + bool flipped; +}; +struct d7s *d7s_device; + +/* + * Register block address- see header for details + * ----------------------------------------- + * | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 | + * ----------------------------------------- + * + * DP - Toggles decimal point on/off + * ALARM - Toggles "Alarm" LED green/red + * FLIP - Inverts display for upside-down mounted board + * bits 0-4 - 7-segment display contents + */ +static atomic_t d7s_users = ATOMIC_INIT(0); + +static int d7s_open(struct inode *inode, struct file *f) +{ + if (D7S_MINOR != iminor(inode)) + return -ENODEV; + atomic_inc(&d7s_users); + return 0; +} + +static int d7s_release(struct inode *inode, struct file *f) +{ + /* Reset flipped state to OBP default only if + * no other users have the device open and we + * are not operating in solaris-compat mode + */ + if (atomic_dec_and_test(&d7s_users) && !sol_compat) { + struct d7s *p = d7s_device; + u8 regval = 0; + + regval = readb(p->regs); + if (p->flipped) + regval |= D7S_FLIP; + else + regval &= ~D7S_FLIP; + writeb(regval, p->regs); + } + + return 0; +} + +static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct d7s *p = d7s_device; + u8 regs = readb(p->regs); + int error = 0; + u8 ireg = 0; + + if (D7S_MINOR != iminor(file_inode(file))) + return -ENODEV; + + mutex_lock(&d7s_mutex); + switch (cmd) { + case D7SIOCWR: + /* assign device register values we mask-out D7S_FLIP + * if in sol_compat mode + */ + if (get_user(ireg, (int __user *) arg)) { + error = -EFAULT; + break; + } + if (sol_compat) { + if (regs & D7S_FLIP) + ireg |= D7S_FLIP; + else + ireg &= ~D7S_FLIP; + } + writeb(ireg, p->regs); + break; + + case D7SIOCRD: + /* retrieve device register values + * NOTE: Solaris implementation returns D7S_FLIP bit + * as toggled by user, even though it does not honor it. + * This driver will not misinform you about the state + * of your hardware while in sol_compat mode + */ + if (put_user(regs, (int __user *) arg)) { + error = -EFAULT; + break; + } + break; + + case D7SIOCTM: + /* toggle device mode-- flip display orientation */ + regs ^= D7S_FLIP; + writeb(regs, p->regs); + break; + } + mutex_unlock(&d7s_mutex); + + return error; +} + +static const struct file_operations d7s_fops = { + .owner = THIS_MODULE, + .unlocked_ioctl = d7s_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .open = d7s_open, + .release = d7s_release, + .llseek = noop_llseek, +}; + +static struct miscdevice d7s_miscdev = { + .minor = D7S_MINOR, + .name = DRIVER_NAME, + .fops = &d7s_fops +}; + +static int d7s_probe(struct platform_device *op) +{ + struct device_node *opts; + int err = -EINVAL; + struct d7s *p; + u8 regs; + + if (d7s_device) + goto out; + + p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL); + err = -ENOMEM; + if (!p) + goto out; + + p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s"); + if (!p->regs) { + printk(KERN_ERR PFX "Cannot map chip registers\n"); + goto out; + } + + err = misc_register(&d7s_miscdev); + if (err) { + printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n", + D7S_MINOR); + goto out_iounmap; + } + + /* OBP option "d7s-flipped?" is honored as default for the + * device, and reset default when detached + */ + regs = readb(p->regs); + opts = of_find_node_by_path("/options"); + if (opts && + of_get_property(opts, "d7s-flipped?", NULL)) + p->flipped = true; + + if (p->flipped) + regs |= D7S_FLIP; + else + regs &= ~D7S_FLIP; + + writeb(regs, p->regs); + + printk(KERN_INFO PFX "7-Segment Display%pOF at [%s:0x%llx] %s\n", + op->dev.of_node, + (regs & D7S_FLIP) ? " (FLIPPED)" : "", + op->resource[0].start, + sol_compat ? "in sol_compat mode" : ""); + + dev_set_drvdata(&op->dev, p); + d7s_device = p; + err = 0; + of_node_put(opts); + +out: + return err; + +out_iounmap: + of_iounmap(&op->resource[0], p->regs, sizeof(u8)); + goto out; +} + +static int d7s_remove(struct platform_device *op) +{ + struct d7s *p = dev_get_drvdata(&op->dev); + u8 regs = readb(p->regs); + + /* Honor OBP d7s-flipped? unless operating in solaris-compat mode */ + if (sol_compat) { + if (p->flipped) + regs |= D7S_FLIP; + else + regs &= ~D7S_FLIP; + writeb(regs, p->regs); + } + + misc_deregister(&d7s_miscdev); + of_iounmap(&op->resource[0], p->regs, sizeof(u8)); + + return 0; +} + +static const struct of_device_id d7s_match[] = { + { + .name = "display7seg", + }, + {}, +}; +MODULE_DEVICE_TABLE(of, d7s_match); + +static struct platform_driver d7s_driver = { + .driver = { + .name = DRIVER_NAME, + .of_match_table = d7s_match, + }, + .probe = d7s_probe, + .remove = d7s_remove, +}; + +module_platform_driver(d7s_driver); |