linux/drivers/video/fbdev/n411.c
David Howells c729203def Annotate hardware config module parameters in drivers/video/
When the kernel is running in secure boot mode, we lock down the kernel to
prevent userspace from modifying the running kernel image.  Whilst this
includes prohibiting access to things like /dev/mem, it must also prevent
access by means of configuring driver modules in such a way as to cause a
device to access or modify the kernel image.

To this end, annotate module_param* statements that refer to hardware
configuration and indicate for future reference what type of parameter they
specify.  The parameter parser in the core sees this information and can
skip such parameters with an error message if the kernel is locked down.
The module initialisation then runs as normal, but just sees whatever the
default values for those parameters is.

Note that we do still need to do the module initialisation because some
drivers have viable defaults set in case parameters aren't specified and
some drivers support automatic configuration (e.g. PNP or PCI) in addition
to manually coded parameters.

This patch annotates drivers in drivers/video/.

Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
cc: linux-fbdev@vger.kernel.org
2017-04-20 12:02:32 +01:00

209 lines
4.9 KiB
C

/*
* linux/drivers/video/n411.c -- Platform device for N411 EPD kit
*
* Copyright (C) 2008, Jaya Kumar
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of this archive for
* more details.
*
* Layout is based on skeletonfb.c by James Simmons and Geert Uytterhoeven.
*
* This driver is written to be used with the Hecuba display controller
* board, and tested with the EInk 800x600 display in 1 bit mode.
* The interface between Hecuba and the host is TTL based GPIO. The
* GPIO requirements are 8 writable data lines and 6 lines for control.
* Only 4 of the controls are actually used here but 6 for future use.
* The driver requires the IO addresses for data and control GPIO at
* load time. It is also possible to use this display with a standard
* PC parallel port.
*
* General notes:
* - User must set dio_addr=0xIOADDR cio_addr=0xIOADDR c2io_addr=0xIOADDR
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/uaccess.h>
#include <linux/irq.h>
#include <video/hecubafb.h>
static unsigned long dio_addr;
static unsigned long cio_addr;
static unsigned long c2io_addr;
static unsigned long splashval;
static unsigned int nosplash;
static unsigned char ctl;
static void n411_set_ctl(struct hecubafb_par *par, unsigned char bit, unsigned
char state)
{
switch (bit) {
case HCB_CD_BIT:
if (state)
ctl &= ~(HCB_CD_BIT);
else
ctl |= HCB_CD_BIT;
break;
case HCB_DS_BIT:
if (state)
ctl &= ~(HCB_DS_BIT);
else
ctl |= HCB_DS_BIT;
break;
}
outb(ctl, cio_addr);
}
static unsigned char n411_get_ctl(struct hecubafb_par *par)
{
return inb(c2io_addr);
}
static void n411_set_data(struct hecubafb_par *par, unsigned char value)
{
outb(value, dio_addr);
}
static void n411_wait_for_ack(struct hecubafb_par *par, int clear)
{
int timeout;
unsigned char tmp;
timeout = 500;
do {
tmp = n411_get_ctl(par);
if ((tmp & HCB_ACK_BIT) && (!clear))
return;
else if (!(tmp & HCB_ACK_BIT) && (clear))
return;
udelay(1);
} while (timeout--);
printk(KERN_ERR "timed out waiting for ack\n");
}
static int n411_init_control(struct hecubafb_par *par)
{
unsigned char tmp;
/* for init, we want the following setup to be set:
WUP = lo
ACK = hi
DS = hi
RW = hi
CD = lo
*/
/* write WUP to lo, DS to hi, RW to hi, CD to lo */
ctl = HCB_WUP_BIT | HCB_RW_BIT | HCB_CD_BIT ;
n411_set_ctl(par, HCB_DS_BIT, 1);
/* check ACK is not lo */
tmp = n411_get_ctl(par);
if (tmp & HCB_ACK_BIT) {
printk(KERN_ERR "Fail because ACK is already low\n");
return -ENXIO;
}
return 0;
}
static int n411_init_board(struct hecubafb_par *par)
{
int retval;
retval = n411_init_control(par);
if (retval)
return retval;
par->send_command(par, APOLLO_INIT_DISPLAY);
par->send_data(par, 0x81);
/* have to wait while display resets */
udelay(1000);
/* if we were told to splash the screen, we just clear it */
if (!nosplash) {
par->send_command(par, APOLLO_ERASE_DISPLAY);
par->send_data(par, splashval);
}
return 0;
}
static struct hecuba_board n411_board = {
.owner = THIS_MODULE,
.init = n411_init_board,
.set_ctl = n411_set_ctl,
.set_data = n411_set_data,
.wait_for_ack = n411_wait_for_ack,
};
static struct platform_device *n411_device;
static int __init n411_init(void)
{
int ret;
if (!dio_addr || !cio_addr || !c2io_addr) {
printk(KERN_WARNING "no IO addresses supplied\n");
return -EINVAL;
}
/* request our platform independent driver */
request_module("hecubafb");
n411_device = platform_device_alloc("hecubafb", -1);
if (!n411_device)
return -ENOMEM;
ret = platform_device_add_data(n411_device, &n411_board,
sizeof(n411_board));
if (ret)
goto put_plat_device;
/* this _add binds hecubafb to n411. hecubafb refcounts n411 */
ret = platform_device_add(n411_device);
if (ret)
goto put_plat_device;
return 0;
put_plat_device:
platform_device_put(n411_device);
return ret;
}
static void __exit n411_exit(void)
{
platform_device_unregister(n411_device);
}
module_init(n411_init);
module_exit(n411_exit);
module_param(nosplash, uint, 0);
MODULE_PARM_DESC(nosplash, "Disable doing the splash screen");
module_param_hw(dio_addr, ulong, ioport, 0);
MODULE_PARM_DESC(dio_addr, "IO address for data, eg: 0x480");
module_param_hw(cio_addr, ulong, ioport, 0);
MODULE_PARM_DESC(cio_addr, "IO address for control, eg: 0x400");
module_param_hw(c2io_addr, ulong, ioport, 0);
MODULE_PARM_DESC(c2io_addr, "IO address for secondary control, eg: 0x408");
module_param(splashval, ulong, 0);
MODULE_PARM_DESC(splashval, "Splash pattern: 0x00 is black, 0x01 is white");
MODULE_DESCRIPTION("board driver for n411 hecuba/apollo epd kit");
MODULE_AUTHOR("Jaya Kumar");
MODULE_LICENSE("GPL");