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w1-gpio-cl.c
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w1-gpio-cl.c
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/*
* w1-gpio-cl
* Command line configured gpio w1 bus master driver
*
* Copyright (c) 2016 Piotr Stolarz <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/gpio.h>
#if !defined(CONFIG_GPIOLIB) || !CONFIG_GPIOLIB
# error Kernel need to be configured with GPIOLIB support
#endif
#if (!defined(CONFIG_W1) || !CONFIG_W1) && \
(!defined(CONFIG_W1_MODULE) || !CONFIG_W1_MODULE)
# error Kernel need to be configured with W1 support
#endif
#if !defined(CONFIG_W1_MAST_MAX) || CONFIG_W1_MAST_MAX <= 0
# error Incorrect or undefined CONFIG_W1_MAST_MAX
#endif
#include "w1/w1_int.h"
#include "gen-mast.h"
#define MODULE_NAME "w1-gpio-cl"
#define LOG_PREF MODULE_NAME ": "
/* negative means not valid (not set, freed) */
#define GPIO_VALID(g) ((g) >= 0)
struct mast_dta
{
/* config spec. */
int gdt; /* data wire gpio */
int od; /* data wire gpio is an open drain type of output (bool) */
int bpu; /* strong pull-up via data wire bit-banging (bool) */
int gpu; /* strong pull-up controlling gpio */
int rev; /* reverse logic for 'gpu' gpio (bool) */
/* w1 bus master handle */
struct w1_bus_master master;
int add; /* successfully added to the main driver (bool) */
};
static int n_mast;
static struct mast_dta mast_dtas[CONFIG_W1_MAST_MAX];
/*
* NOTE: In all the callbacks handlers below there is a need to check gpio
* validity before its use, since the gpio may be in the "already-freed"
* state due to module's clean-up (unloading) process.
*/
/*
* w1 bus master bit read callback.
*/
static u8 w1_read_bit(void *data)
{
volatile struct mast_dta *mdt = (struct mast_dta*)data;
if (GPIO_VALID(mdt->gdt))
return (gpio_get_value(mdt->gdt) ? 1 : 0);
else
/* "normal state" of an open-drain medium is high */
return 1;
}
/*
* w1 bus master bit write callback.
*/
static void w1_write_bit(void *data, u8 bit)
{
volatile struct mast_dta *mdt = (struct mast_dta*)data;
if (GPIO_VALID(mdt->gdt)) {
if (bit)
gpio_direction_input(mdt->gdt);
else
gpio_direction_output(mdt->gdt, 0);
}
}
/*
* w1 bus strong pull-up bit-banging callback: data wire bit-banging.
*/
static void w1_bitbang_pullup_bpu(void *data, u8 on)
{
volatile struct mast_dta *mdt = (struct mast_dta*)data;
if (GPIO_VALID(mdt->gdt)) {
if (on)
gpio_direction_output(mdt->gdt, 1);
else
gpio_direction_input(mdt->gdt);
}
}
/*
* w1 bus strong pull-up bit-banging callback: controlling via 'gpu' gpio.
*/
static void w1_bitbang_pullup_gpu(void *data, u8 on)
{
volatile struct mast_dta *mdt = (struct mast_dta*)data;
if (GPIO_VALID(mdt->gpu)) {
if (on)
gpio_set_value(mdt->gpu, (mdt->rev ? 1 : 0));
else
gpio_set_value(mdt->gpu, (mdt->rev ? 0 : 1));
}
}
/*
* Get a token for parse_mast_conf().
*/
static size_t get_tkn(const char **p_str, const char **p_tkn)
{
char c;
/* cut leading spaces */
while ((c=**p_str, c==' ' || c=='\t')) (*p_str)++;
*p_tkn = *p_str;
for (; (c=**p_str, c && c!=' ' && c!='\t'); (*p_str)++) {
if (!((c >= '0' && c <= '9') ||
(c >= 'a' && c <= 'z') ||
(c >= 'A' && c <= 'Z')))
{
if (*p_str == *p_tkn) (*p_str)++;
break;
}
}
return *p_str - *p_tkn;
}
/*
* Parse w1 bus master conf argument and write a result under mast_dta struct.
* If success 0 is returned. In case some parameter is absent in the conf,
* default value is assumed.
*/
static int parse_mast_conf(const char *arg, struct mast_dta *mdt)
{
int val;
const char *tkn;
size_t ltkn;
/* "exist" flags */
struct {
unsigned gdt :1;
unsigned od :1;
unsigned bpu :1;
unsigned gpu :1;
unsigned rev :1;
unsigned val :1;
} exts = {0};
/* set defaults */
mdt->gdt = mdt->gpu = -1; /* not valid */
mdt->od = mdt->bpu = mdt->rev = 0;
for (ltkn = get_tkn(&arg, &tkn);
ltkn;
exts.gdt = exts.od = exts.bpu =
exts.gpu = exts.rev =exts.val = 0)
{
/* param name */
if (!strncmp(tkn, "gdt", ltkn)) {
exts.gdt = 1;
} else
if (!strncmp(tkn, "od", ltkn)) {
exts.od = 1;
} else
if (!strncmp(tkn, "bpu", ltkn)) {
exts.bpu = 1;
} else
if (!strncmp(tkn, "gpu", ltkn)) {
exts.gpu = 1;
} else
if (!strncmp(tkn, "rev", ltkn)) {
exts.rev = 1;
} else {
/* unknown param */
return -EINVAL;
}
/* value existence */
ltkn = get_tkn(&arg, &tkn);
if (ltkn > 0) {
if (*tkn==':' || *tkn=='=') {
ltkn = get_tkn(&arg, &tkn);
if (ltkn) exts.val = 1;
} else
if (*tkn==',' || *tkn==';') {
ltkn = get_tkn(&arg, &tkn);
} else {
/* malformed */
return -EINVAL;
}
}
/* value parsing */
if (exts.gdt || exts.gpu) {
if (exts.val)
{
/* integer */
for (val=0; tkn<arg; tkn++) {
if (*tkn>='0' && *tkn<='9') {
val = val*10 + *tkn-'0';
} else {
/* parsing error */
return -EINVAL;
}
}
if (exts.gdt)
mdt->gdt = val;
else
mdt->gpu = val;
} else {
/* value is required */
return -EINVAL;
}
} else {
/* od, bpu, rev */
if (exts.val)
{
/* bool */
if (tkn-arg==1 && (*tkn=='1' ||
*tkn=='y' || *tkn=='Y'))
{
val = 1;
} else
if (tkn-arg==1 && (*tkn=='0' ||
*tkn=='n' || *tkn=='N'))
{
val = 0;
} else {
/* parsing error */
return -EINVAL;
}
} else {
/* if no value is provided assume 1 */
val = 1;
}
if (exts.od)
mdt->od = val;
else if (exts.bpu)
mdt->bpu = val;
else
mdt->rev = val;
}
/* get the next token (if required) */
if (exts.val) {
ltkn = get_tkn(&arg, &tkn);
if (ltkn > 0) {
if (*tkn!=',' && *tkn!=';') {
/* malformed */
return -EINVAL;
}
ltkn = get_tkn(&arg, &tkn);
}
}
}
return 0;
}
/*
* Module clean-up.
*/
void cleanup_module(void)
{
int i, gpio;
for (i=0; i < n_mast; i++) {
if (GPIO_VALID(mast_dtas[i].gdt)) {
gpio = mast_dtas[i].gdt;
mast_dtas[i].gdt = -1;
gpio_free(gpio);
}
if (GPIO_VALID(mast_dtas[i].gpu)) {
gpio = mast_dtas[i].gpu;
mast_dtas[i].gpu = -1;
gpio_free(gpio);
}
if (mast_dtas[i].add) {
w1_remove_master_device(&mast_dtas[i].master);
mast_dtas[i].add = 0;
}
}
n_mast = 0;
}
/*
* Module initialization.
*/
int init_module(void)
{
int i, ret=0, res;
struct mast_dta mdt;
const char *marg;
n_mast = 0;
memset(&mdt.master, 0, sizeof(mdt.master));
mdt.add = 0;
mdt.master.read_bit = w1_read_bit;
mdt.master.write_bit = w1_write_bit;
for (i=0; i<CONFIG_W1_MAST_MAX; i++) {
if (!(marg = get_mast_arg(i))) continue;
if ((ret = parse_mast_conf(marg, &mdt)) != 0) {
printk(KERN_ERR LOG_PREF
"Invalid arg format; m%d <%s>\n", i+1, marg);
goto finish;
}
if (!GPIO_VALID(mdt.gdt) || !gpio_is_valid(mdt.gdt)) {
printk(KERN_ERR LOG_PREF
"Invalid or not provided 'gdt' gpio;"
" m%d <%s>\n", i+1, marg);
ret = -EINVAL;
goto finish;
}
if (GPIO_VALID(mdt.gpu) && !gpio_is_valid(mdt.gpu)) {
printk(KERN_ERR LOG_PREF
"Invalid 'gpu' gpio; m%d <%s>\n", i+1, marg);
ret = -EINVAL;
goto finish;
}
if (mdt.od && (!GPIO_VALID(mdt.gpu) && mdt.bpu)) {
printk(KERN_ERR LOG_PREF
"Can't enable data wire strong pull-up "
"bit-banging for an open-drain gpio; "
"m%d <%s>\n", i+1, marg);
ret = -EINVAL;
goto finish;
}
if (!mdt.od && (GPIO_VALID(mdt.gpu) && mdt.bpu)) {
printk(KERN_ERR LOG_PREF
"Be specific if strong pull-up should be "
"enabled via the data wire bit-banging or an "
"external gpio; m%d <%s>", i+1, marg);
ret = -EINVAL;
goto finish;
}
if ((ret = gpio_request_one(mdt.gdt,
GPIOF_IN | (mdt.od ? GPIOF_OPEN_DRAIN : 0),
MODULE_NAME)) != 0)
{
printk(KERN_ERR LOG_PREF
"%d gpio request error: %d; m%d <%s>",
mdt.gdt, ret, i+1, marg);
goto finish;
}
if (GPIO_VALID(mdt.gpu) &&
(ret = gpio_request_one(mdt.gpu,
(mdt.rev ?
GPIOF_OUT_INIT_LOW :
GPIOF_OUT_INIT_HIGH),
MODULE_NAME)) != 0)
{
printk(KERN_ERR LOG_PREF
"%d gpio request error: %d; m%d <%s>",
mdt.gpu, ret, i+1, marg);
goto finish;
}
mdt.master.data = &mast_dtas[n_mast];
if (GPIO_VALID(mdt.gpu))
mdt.master.bitbang_pullup = w1_bitbang_pullup_gpu;
else if (mdt.bpu)
mdt.master.bitbang_pullup = w1_bitbang_pullup_bpu;
mast_dtas[n_mast++] = mdt;
}
if (!n_mast) {
printk(KERN_ERR LOG_PREF
"No w1 bus master(s) specification. Exiting...");
ret = -EINVAL;
goto finish;
}
/*
* NOTE: There were observed deadlocks on the main driver ref-counters
* during bus masters removal due to unsuccessful module initialization
* (probably an issue with bus masters kernel threads start-ups). For
* this reason the bus masters registration process doesn't lead to
* the module initialization failure, and any problems at this stage
* are only printk'ed.
* On the other hand, failure here is rather uncommon.
*/
for (i=0; i < n_mast; i++) {
if ((res = w1_add_master_device(&mast_dtas[i].master)) != 0) {
printk(KERN_ERR LOG_PREF
"w1_add_master_device error: %d", res);
} else
mast_dtas[i].add = 1;
}
finish:
if (ret) cleanup_module();
return ret;
}
MODULE_VERSION("1.0");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Command line configured gpio w1 bus master driver");
MODULE_AUTHOR("Piotr Stolarz <[email protected]>");
/* vim: set noet ts=8 sw=8 sts=0: */