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![David Howells](/assets/img/avatar_default.png)
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/i2c/. Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Wolfram Sang <wsa@the-dreams.de> Acked-by: Jean Delvare <jdelvare@suse.de> cc: linux-i2c@vger.kernel.org
212 lines
5 KiB
C
212 lines
5 KiB
C
/*
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* i2c-pca-isa.c driver for PCA9564 on ISA boards
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* Copyright (C) 2004 Arcom Control Systems
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* Copyright (C) 2008 Pengutronix
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/ioport.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/delay.h>
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#include <linux/jiffies.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/wait.h>
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#include <linux/isa.h>
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#include <linux/i2c.h>
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#include <linux/i2c-algo-pca.h>
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#include <linux/io.h>
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#include <asm/irq.h>
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#define DRIVER "i2c-pca-isa"
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#define IO_SIZE 4
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static unsigned long base;
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static int irq = -1;
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/* Data sheet recommends 59kHz for 100kHz operation due to variation
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* in the actual clock rate */
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static int clock = 59000;
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static struct i2c_adapter pca_isa_ops;
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static wait_queue_head_t pca_wait;
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static void pca_isa_writebyte(void *pd, int reg, int val)
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{
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#ifdef DEBUG_IO
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static char *names[] = { "T/O", "DAT", "ADR", "CON" };
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printk(KERN_DEBUG "*** write %s at %#lx <= %#04x\n", names[reg],
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base+reg, val);
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#endif
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outb(val, base+reg);
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}
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static int pca_isa_readbyte(void *pd, int reg)
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{
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int res = inb(base+reg);
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#ifdef DEBUG_IO
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{
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static char *names[] = { "STA", "DAT", "ADR", "CON" };
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printk(KERN_DEBUG "*** read %s => %#04x\n", names[reg], res);
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}
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#endif
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return res;
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}
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static int pca_isa_waitforcompletion(void *pd)
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{
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unsigned long timeout;
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long ret;
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if (irq > -1) {
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ret = wait_event_timeout(pca_wait,
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pca_isa_readbyte(pd, I2C_PCA_CON)
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& I2C_PCA_CON_SI, pca_isa_ops.timeout);
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} else {
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/* Do polling */
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timeout = jiffies + pca_isa_ops.timeout;
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do {
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ret = time_before(jiffies, timeout);
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if (pca_isa_readbyte(pd, I2C_PCA_CON)
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& I2C_PCA_CON_SI)
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break;
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udelay(100);
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} while (ret);
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}
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return ret > 0;
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}
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static void pca_isa_resetchip(void *pd)
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{
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/* apparently only an external reset will do it. not a lot can be done */
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printk(KERN_WARNING DRIVER ": Haven't figured out how to do a reset yet\n");
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}
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static irqreturn_t pca_handler(int this_irq, void *dev_id) {
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wake_up(&pca_wait);
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return IRQ_HANDLED;
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}
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static struct i2c_algo_pca_data pca_isa_data = {
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/* .data intentionally left NULL, not needed with ISA */
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.write_byte = pca_isa_writebyte,
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.read_byte = pca_isa_readbyte,
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.wait_for_completion = pca_isa_waitforcompletion,
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.reset_chip = pca_isa_resetchip,
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};
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static struct i2c_adapter pca_isa_ops = {
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.owner = THIS_MODULE,
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.algo_data = &pca_isa_data,
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.name = "PCA9564/PCA9665 ISA Adapter",
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.timeout = HZ,
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};
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static int pca_isa_match(struct device *dev, unsigned int id)
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{
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int match = base != 0;
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if (match) {
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if (irq <= -1)
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dev_warn(dev, "Using polling mode (specify irq)\n");
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} else
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dev_err(dev, "Please specify I/O base\n");
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return match;
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}
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static int pca_isa_probe(struct device *dev, unsigned int id)
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{
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init_waitqueue_head(&pca_wait);
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dev_info(dev, "i/o base %#08lx. irq %d\n", base, irq);
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#ifdef CONFIG_PPC
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if (check_legacy_ioport(base)) {
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dev_err(dev, "I/O address %#08lx is not available\n", base);
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goto out;
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}
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#endif
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if (!request_region(base, IO_SIZE, "i2c-pca-isa")) {
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dev_err(dev, "I/O address %#08lx is in use\n", base);
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goto out;
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}
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if (irq > -1) {
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if (request_irq(irq, pca_handler, 0, "i2c-pca-isa", &pca_isa_ops) < 0) {
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dev_err(dev, "Request irq%d failed\n", irq);
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goto out_region;
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}
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}
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pca_isa_data.i2c_clock = clock;
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if (i2c_pca_add_bus(&pca_isa_ops) < 0) {
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dev_err(dev, "Failed to add i2c bus\n");
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goto out_irq;
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}
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return 0;
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out_irq:
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if (irq > -1)
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free_irq(irq, &pca_isa_ops);
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out_region:
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release_region(base, IO_SIZE);
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out:
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return -ENODEV;
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}
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static int pca_isa_remove(struct device *dev, unsigned int id)
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{
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i2c_del_adapter(&pca_isa_ops);
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if (irq > -1) {
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disable_irq(irq);
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free_irq(irq, &pca_isa_ops);
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}
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release_region(base, IO_SIZE);
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return 0;
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}
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static struct isa_driver pca_isa_driver = {
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.match = pca_isa_match,
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.probe = pca_isa_probe,
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.remove = pca_isa_remove,
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.driver = {
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.owner = THIS_MODULE,
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.name = DRIVER,
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}
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};
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MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
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MODULE_DESCRIPTION("ISA base PCA9564/PCA9665 driver");
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MODULE_LICENSE("GPL");
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module_param_hw(base, ulong, ioport, 0);
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MODULE_PARM_DESC(base, "I/O base address");
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module_param_hw(irq, int, irq, 0);
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MODULE_PARM_DESC(irq, "IRQ");
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module_param(clock, int, 0);
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MODULE_PARM_DESC(clock, "Clock rate in hertz.\n\t\t"
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"For PCA9564: 330000,288000,217000,146000,"
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"88000,59000,44000,36000\n"
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"\t\tFor PCA9665:\tStandard: 60300 - 100099\n"
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"\t\t\t\tFast: 100100 - 400099\n"
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"\t\t\t\tFast+: 400100 - 10000099\n"
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"\t\t\t\tTurbo: Up to 1265800");
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module_isa_driver(pca_isa_driver, 1);
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