platform/iris/iris.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Eurobraille/Iris power off support.
0004  *
0005  * Eurobraille's Iris machine is a PC with no APM or ACPI support.
0006  * It is shutdown by a special I/O sequence which this module provides.
0007  *
0008  *  Copyright (C) Shérab <Sebastien.Hinderer@ens-lyon.org>
0009  */
0010
0011 #include <linux/moduleparam.h>
0012 #include <linux/module.h>
0013 #include <linux/platform_device.h>
0014 #include <linux/kernel.h>
0015 #include <linux/errno.h>
0016 #include <linux/delay.h>
0017 #include <linux/pm.h>
0018 #include <asm/io.h>
0019
0020 #define IRIS_GIO_BASE       0x340
0021 #define IRIS_GIO_INPUT      IRIS_GIO_BASE
0022 #define IRIS_GIO_OUTPUT     (IRIS_GIO_BASE + 1)
0023 #define IRIS_GIO_PULSE      0x80 /* First byte to send */
0024 #define IRIS_GIO_REST       0x00 /* Second byte to send */
0025 #define IRIS_GIO_NODEV      0xff /* Likely not an Iris */
0026
0027 MODULE_LICENSE("GPL");
0028 MODULE_AUTHOR("Sébastien Hinderer <Sebastien.Hinderer@ens-lyon.org>");
0029 MODULE_DESCRIPTION("A power_off handler for Iris devices from EuroBraille");
0030
0031 static bool force;
0032
0033 module_param(force, bool, 0);
0034 MODULE_PARM_DESC(force, "Set to one to force poweroff handler installation.");
0035
0036 static void (*old_pm_power_off)(void);
0037
0038 static void iris_power_off(void)
0039 {
0040     outb(IRIS_GIO_PULSE, IRIS_GIO_OUTPUT);
0041     msleep(850);
0042     outb(IRIS_GIO_REST, IRIS_GIO_OUTPUT);
0043 }
0044
0045 /*
0046  * Before installing the power_off handler, try to make sure the OS is
0047  * running on an Iris.  Since Iris does not support DMI, this is done
0048  * by reading its input port and seeing whether the read value is
0049  * meaningful.
0050  */
0051 static int iris_probe(struct platform_device *pdev)
0052 {
0053     unsigned char status = inb(IRIS_GIO_INPUT);
0054     if (status == IRIS_GIO_NODEV) {
0055         printk(KERN_ERR "This machine does not seem to be an Iris. "
0056             "Power off handler not installed.\n");
0057         return -ENODEV;
0058     }
0059     old_pm_power_off = pm_power_off;
0060     pm_power_off = &iris_power_off;
0061     printk(KERN_INFO "Iris power_off handler installed.\n");
0062     return 0;
0063 }
0064
0065 static int iris_remove(struct platform_device *pdev)
0066 {
0067     pm_power_off = old_pm_power_off;
0068     printk(KERN_INFO "Iris power_off handler uninstalled.\n");
0069     return 0;
0070 }
0071
0072 static struct platform_driver iris_driver = {
0073     .driver     = {
0074         .name   = "iris",
0075     },
0076     .probe          = iris_probe,
0077     .remove         = iris_remove,
0078 };
0079
0080 static struct resource iris_resources[] = {
0081     {
0082         .start  = IRIS_GIO_BASE,
0083         .end    = IRIS_GIO_OUTPUT,
0084         .flags  = IORESOURCE_IO,
0085         .name   = "address"
0086     }
0087 };
0088
0089 static struct platform_device *iris_device;
0090
0091 static int iris_init(void)
0092 {
0093     int ret;
0094     if (force != 1) {
0095         printk(KERN_ERR "The force parameter has not been set to 1."
0096             " The Iris poweroff handler will not be installed.\n");
0097         return -ENODEV;
0098     }
0099     ret = platform_driver_register(&iris_driver);
0100     if (ret < 0) {
0101         printk(KERN_ERR "Failed to register iris platform driver: %d\n",
0102             ret);
0103         return ret;
0104     }
0105     iris_device = platform_device_register_simple("iris", (-1),
0106                 iris_resources, ARRAY_SIZE(iris_resources));
0107     if (IS_ERR(iris_device)) {
0108         printk(KERN_ERR "Failed to register iris platform device\n");
0109         platform_driver_unregister(&iris_driver);
0110         return PTR_ERR(iris_device);
0111     }
0112     return 0;
0113 }
0114
0115 static void iris_exit(void)
0116 {
0117     platform_device_unregister(iris_device);
0118     platform_driver_unregister(&iris_driver);
0119 }
0120
0121 module_init(iris_init);
0122 module_exit(iris_exit);