Commit 278429cf authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'i2c-for-linus' of git://

* 'i2c-for-linus' of git://
  i2c-viapro: Add support for SMBus Process Call transactions
  i2c: Restore i2c_smbus_process_call function
  i2c: Do earlier driver model init
  i2c: Only build Tyan SMBus mux drivers on x86
  i2c: Guard against oopses from bad init sequences
  i2c: Document the implementation details of the /dev interface
  i2c: Improve dev-interface documentation
  i2c-parport-light: Don't register a platform device resource
  hwmon: (dme1737) Convert to a new-style i2c driver
  hwmon: (dme1737) Be less i2c-centric
  i2c/tps65010: Vibrator hookup to gpiolib
  i2c-viapro: Add VX800/VX820 support
  i2c: Renesas Highlander FPGA SMBus support
  i2c-pca-isa: Don't grab arbitrary resources
  i2c/isp1301_omap: Convert to a new-style i2c driver, part 2
  i2c/isp1301_omap: Convert to a new-style i2c driver, part 1
parents e413b210 a05f2c5a
......@@ -16,6 +16,9 @@ Supported adapters:
* VIA Technologies, Inc. CX700
Datasheet: available on request and under NDA from VIA
* VIA Technologies, Inc. VX800/VX820
Datasheet: available on
Kyösti Mälkki <>,
Mark D. Studebaker <>,
......@@ -49,6 +52,7 @@ Your lspci -n listing must show one of these :
device 1106:3372 (VT8237S)
device 1106:3287 (VT8251)
device 1106:8324 (CX700)
device 1106:8353 (VX800/VX820)
If none of these show up, you should look in the BIOS for settings like
enable ACPI / SMBus or even USB.
......@@ -57,5 +61,5 @@ Except for the oldest chips (VT82C596A/B, VT82C686A and most probably
VT8231), this driver supports I2C block transactions. Such transactions
are mainly useful to read from and write to EEPROMs.
The CX700 additionally appears to support SMBus PEC, although this driver
doesn't implement it yet.
The CX700/VX800/VX820 additionally appears to support SMBus PEC, although
this driver doesn't implement it yet.
......@@ -4,6 +4,10 @@ the /dev interface. You need to load module i2c-dev for this.
Each registered i2c adapter gets a number, counting from 0. You can
examine /sys/class/i2c-dev/ to see what number corresponds to which adapter.
Alternatively, you can run "i2cdetect -l" to obtain a formated list of all
i2c adapters present on your system at a given time. i2cdetect is part of
the i2c-tools package.
I2C device files are character device files with major device number 89
and a minor device number corresponding to the number assigned as
explained above. They should be called "i2c-%d" (i2c-0, i2c-1, ...,
......@@ -17,30 +21,34 @@ So let's say you want to access an i2c adapter from a C program. The
first thing to do is "#include <linux/i2c-dev.h>". Please note that
there are two files named "i2c-dev.h" out there, one is distributed
with the Linux kernel and is meant to be included from kernel
driver code, the other one is distributed with lm_sensors and is
driver code, the other one is distributed with i2c-tools and is
meant to be included from user-space programs. You obviously want
the second one here.
Now, you have to decide which adapter you want to access. You should
inspect /sys/class/i2c-dev/ to decide this. Adapter numbers are assigned
somewhat dynamically, so you can not even assume /dev/i2c-0 is the
first adapter.
inspect /sys/class/i2c-dev/ or run "i2cdetect -l" to decide this.
Adapter numbers are assigned somewhat dynamically, so you can not
assume much about them. They can even change from one boot to the next.
Next thing, open the device file, as follows:
int file;
int adapter_nr = 2; /* probably dynamically determined */
char filename[20];
if ((file = open(filename,O_RDWR)) < 0) {
snprintf(filename, 19, "/dev/i2c-%d", adapter_nr);
file = open(filename, O_RDWR);
if (file < 0) {
/* ERROR HANDLING; you can check errno to see what went wrong */
When you have opened the device, you must specify with what device
address you want to communicate:
int addr = 0x40; /* The I2C address */
if (ioctl(file,I2C_SLAVE,addr) < 0) {
if (ioctl(file, I2C_SLAVE, addr) < 0) {
/* ERROR HANDLING; you can check errno to see what went wrong */
......@@ -48,31 +56,41 @@ address you want to communicate:
Well, you are all set up now. You can now use SMBus commands or plain
I2C to communicate with your device. SMBus commands are preferred if
the device supports them. Both are illustrated below.
__u8 register = 0x10; /* Device register to access */
__s32 res;
char buf[10];
/* Using SMBus commands */
res = i2c_smbus_read_word_data(file,register);
res = i2c_smbus_read_word_data(file, register);
if (res < 0) {
/* ERROR HANDLING: i2c transaction failed */
} else {
/* res contains the read word */
/* Using I2C Write, equivalent of
i2c_smbus_write_word_data(file,register,0x6543) */
i2c_smbus_write_word_data(file, register, 0x6543) */
buf[0] = register;
buf[1] = 0x43;
buf[2] = 0x65;
if ( write(file,buf,3) != 3) {
if (write(file, buf, 3) ! =3) {
/* ERROR HANDLING: i2c transaction failed */
/* Using I2C Read, equivalent of i2c_smbus_read_byte(file) */
if (read(file,buf,1) != 1) {
if (read(file, buf, 1) != 1) {
/* ERROR HANDLING: i2c transaction failed */
} else {
/* buf[0] contains the read byte */
Note that only a subset of the I2C and SMBus protocols can be achieved by
the means of read() and write() calls. In particular, so-called combined
transactions (mixing read and write messages in the same transaction)
aren't supported. For this reason, this interface is almost never used by
user-space programs.
IMPORTANT: because of the use of inline functions, you *have* to use
'-O' or some variation when you compile your program!
......@@ -80,31 +98,29 @@ IMPORTANT: because of the use of inline functions, you *have* to use
Full interface description
The following IOCTLs are defined and fully supported
(see also i2c-dev.h):
The following IOCTLs are defined:
ioctl(file,I2C_SLAVE,long addr)
ioctl(file, I2C_SLAVE, long addr)
Change slave address. The address is passed in the 7 lower bits of the
argument (except for 10 bit addresses, passed in the 10 lower bits in this
ioctl(file,I2C_TENBIT,long select)
ioctl(file, I2C_TENBIT, long select)
Selects ten bit addresses if select not equals 0, selects normal 7 bit
addresses if select equals 0. Default 0. This request is only valid
if the adapter has I2C_FUNC_10BIT_ADDR.
ioctl(file,I2C_PEC,long select)
ioctl(file, I2C_PEC, long select)
Selects SMBus PEC (packet error checking) generation and verification
if select not equals 0, disables if select equals 0. Default 0.
Used only for SMBus transactions. This request only has an effect if the
the adapter has I2C_FUNC_SMBUS_PEC; it is still safe if not, it just
doesn't have any effect.
ioctl(file,I2C_FUNCS,unsigned long *funcs)
ioctl(file, I2C_FUNCS, unsigned long *funcs)
Gets the adapter functionality and puts it in *funcs.
ioctl(file,I2C_RDWR,struct i2c_rdwr_ioctl_data *msgset)
ioctl(file, I2C_RDWR, struct i2c_rdwr_ioctl_data *msgset)
Do combined read/write transaction without stop in between.
Only valid if the adapter has I2C_FUNC_I2C. The argument is
a pointer to a
......@@ -120,10 +136,9 @@ ioctl(file,I2C_RDWR,struct i2c_rdwr_ioctl_data *msgset)
The slave address and whether to use ten bit address mode has to be
set in each message, overriding the values set with the above ioctl's.
Other values are NOT supported at this moment, except for I2C_SMBUS,
which you should never directly call; instead, use the access functions
ioctl(file, I2C_SMBUS, struct i2c_smbus_ioctl_data *args)
Not meant to be called directly; instead, use the access functions
You can do plain i2c transactions by using read(2) and write(2) calls.
You do not need to pass the address byte; instead, set it through
......@@ -148,7 +163,52 @@ what happened. The 'write' transactions return 0 on success; the
returns the number of values read. The block buffers need not be longer
than 32 bytes.
The above functions are all macros, that resolve to calls to the
i2c_smbus_access function, that on its turn calls a specific ioctl
The above functions are all inline functions, that resolve to calls to
the i2c_smbus_access function, that on its turn calls a specific ioctl
with the data in a specific format. Read the source code if you
want to know what happens behind the screens.
Implementation details
For the interested, here's the code flow which happens inside the kernel
when you use the /dev interface to I2C:
1* Your program opens /dev/i2c-N and calls ioctl() on it, as described in
section "C example" above.
2* These open() and ioctl() calls are handled by the i2c-dev kernel
driver: see i2c-dev.c:i2cdev_open() and i2c-dev.c:i2cdev_ioctl(),
respectively. You can think of i2c-dev as a generic I2C chip driver
that can be programmed from user-space.
3* Some ioctl() calls are for administrative tasks and are handled by
i2c-dev directly. Examples include I2C_SLAVE (set the address of the
device you want to access) and I2C_PEC (enable or disable SMBus error
checking on future transactions.)
4* Other ioctl() calls are converted to in-kernel function calls by
i2c-dev. Examples include I2C_FUNCS, which queries the I2C adapter
functionality using i2c.h:i2c_get_functionality(), and I2C_SMBUS, which
performs an SMBus transaction using i2c-core.c:i2c_smbus_xfer().
The i2c-dev driver is responsible for checking all the parameters that
come from user-space for validity. After this point, there is no
difference between these calls that came from user-space through i2c-dev
and calls that would have been performed by kernel I2C chip drivers
directly. This means that I2C bus drivers don't need to implement
anything special to support access from user-space.
5* These i2c-core.c/i2c.h functions are wrappers to the actual
implementation of your I2C bus driver. Each adapter must declare
callback functions implementing these standard calls.
i2c.h:i2c_get_functionality() calls i2c_adapter.algo->functionality(),
while i2c-core.c:i2c_smbus_xfer() calls either
adapter.algo->smbus_xfer() if it is implemented, or if not,
i2c-core.c:i2c_smbus_xfer_emulated() which in turn calls
After your I2C bus driver has processed these requests, execution runs
up the call chain, with almost no processing done, except by i2c-dev to
package the returned data, if any, in suitable format for the ioctl.
......@@ -109,8 +109,8 @@ specified through the Comm byte.
S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A] P
SMBus Process Call
SMBus Process Call: i2c_smbus_process_call()
This command selects a device register (through the Comm byte), sends
16 bits of data to it, and reads 16 bits of data in return.
......@@ -606,6 +606,8 @@ SMBus communication
extern s32 i2c_smbus_read_word_data(struct i2c_client * client, u8 command);
extern s32 i2c_smbus_write_word_data(struct i2c_client * client,
u8 command, u16 value);
extern s32 i2c_smbus_process_call(struct i2c_client *client,
u8 command, u16 value);
extern s32 i2c_smbus_read_block_data(struct i2c_client * client,
u8 command, u8 *values);
extern s32 i2c_smbus_write_block_data(struct i2c_client * client,
......@@ -621,8 +623,6 @@ These ones were removed from i2c-core because they had no users, but could
be added back later if needed:
extern s32 i2c_smbus_write_quick(struct i2c_client * client, u8 value);
extern s32 i2c_smbus_process_call(struct i2c_client * client,
u8 command, u16 value);
extern s32 i2c_smbus_block_process_call(struct i2c_client *client,
u8 command, u8 length,
u8 *values)
......@@ -476,6 +476,10 @@ static struct i2c_board_info __initdata h3_i2c_board_info[] = {
I2C_BOARD_INFO("tps65013", 0x48),
/* .irq = OMAP_GPIO_IRQ(??), */
I2C_BOARD_INFO("isp1301_omap", 0x2d),
.irq = OMAP_GPIO_IRQ(14),
static struct omap_gpio_switch h3_gpio_switches[] __initdata = {
......@@ -18,6 +18,7 @@
#include <linux/mtd/partitions.h>
#include <linux/delay.h>
#include <linux/workqueue.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/err.h>
#include <linux/clk.h>
......@@ -391,6 +392,13 @@ static struct omap_board_config_kernel h4_config[] = {
{ OMAP_TAG_LCD, &h4_lcd_config },
static struct i2c_board_info __initdata h4_i2c_board_info[] = {
I2C_BOARD_INFO("isp1301_omap", 0x2d),
.irq = OMAP_GPIO_IRQ(125),
static void __init omap_h4_init(void)
......@@ -411,6 +419,9 @@ static void __init omap_h4_init(void)
i2c_register_board_info(1, h4_i2c_board_info,
platform_add_devices(h4_devices, ARRAY_SIZE(h4_devices));
omap_board_config = h4_config;
omap_board_config_size = ARRAY_SIZE(h4_config);
This diff is collapsed.
......@@ -55,7 +55,7 @@ config I2C_AMD756
config I2C_AMD756_S4882
tristate "SMBus multiplexing on the Tyan S4882"
depends on I2C_AMD756 && EXPERIMENTAL
depends on I2C_AMD756 && X86 && EXPERIMENTAL
Enabling this option will add specific SMBus support for the Tyan
S4882 motherboard. On this 4-CPU board, the SMBus is multiplexed
......@@ -148,7 +148,7 @@ config I2C_NFORCE2
config I2C_NFORCE2_S4985
tristate "SMBus multiplexing on the Tyan S4985"
depends on I2C_NFORCE2 && X86 && EXPERIMENTAL
Enabling this option will add specific SMBus support for the Tyan
S4985 motherboard. On this 4-CPU board, the SMBus is multiplexed
......@@ -209,7 +209,7 @@ config I2C_VIA
will be called i2c-via.
config I2C_VIAPRO
tristate "VIA VT82C596/82C686/82xx and CX700"
tristate "VIA VT82C596/82C686/82xx and CX700/VX800/VX820"
depends on PCI
If you say yes to this option, support will be included for the VIA
......@@ -223,6 +223,8 @@ config I2C_VIAPRO
This driver can also be built as a module. If so, the module
will be called i2c-viapro.
......@@ -330,6 +332,18 @@ config I2C_GPIO
This is a very simple bitbanging I2C driver utilizing the
arch-neutral GPIO API to control the SCL and SDA lines.
tristate "Highlander FPGA SMBus interface"
depends on SH_HIGHLANDER
If you say yes to this option, support will be included for
the SMBus interface located in the FPGA on various Highlander
boards, particularly the R0P7780LC0011RL and R0P7785LC0011RL
FPGAs. This is wholly unrelated to the SoC I2C.
This driver can also be built as a module. If so, the module
will be called i2c-highlander.
config I2C_IBM_IIC
tristate "IBM PPC 4xx on-chip I2C interface"
depends on 4xx
......@@ -31,6 +31,7 @@ obj-$(CONFIG_I2C_BLACKFIN_TWI) += i2c-bfin-twi.o
obj-$(CONFIG_I2C_CPM) += i2c-cpm.o
obj-$(CONFIG_I2C_DAVINCI) += i2c-davinci.o
obj-$(CONFIG_I2C_GPIO) += i2c-gpio.o
obj-$(CONFIG_I2C_HIGHLANDER) += i2c-highlander.o
obj-$(CONFIG_I2C_IBM_IIC) += i2c-ibm_iic.o
obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o
obj-$(CONFIG_I2C_IXP2000) += i2c-ixp2000.o
* Renesas Solutions Highlander FPGA I2C/SMBus support.
* Supported devices: R0P7780LC0011RL, R0P7785LC0011RL
* Copyright (C) 2008 Paul Mundt
* Copyright (C) 2008 Renesas Solutions Corp.
* Copyright (C) 2008 Atom Create Engineering Co., Ltd.
* This file is subject to the terms and conditions of the GNU General
* Public License version 2. See the file "COPYING" in the main directory
* of this archive for more details.
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/platform_device.h>
#include <linux/completion.h>
#include <linux/io.h>
#include <linux/delay.h>
#define SMCR 0x00
#define SMCR_START (1 << 0)
#define SMCR_IRIC (1 << 1)
#define SMCR_BBSY (1 << 2)
#define SMCR_ACKE (1 << 3)
#define SMCR_RST (1 << 4)
#define SMCR_IEIC (1 << 6)
#define SMSMADR 0x02
#define SMMR 0x04
#define SMMR_MODE0 (1 << 0)
#define SMMR_MODE1 (1 << 1)
#define SMMR_CAP (1 << 3)
#define SMMR_TMMD (1 << 4)
#define SMMR_SP (1 << 7)
#define SMSADR 0x06
#define SMTRDR 0x46
struct highlander_i2c_dev {
struct device *dev;
void __iomem *base;
struct i2c_adapter adapter;
struct completion cmd_complete;
unsigned long last_read_time;
int irq;
u8 *buf;
size_t buf_len;
static int iic_force_poll, iic_force_normal;
static int iic_timeout = 1000, iic_read_delay;
static inline void highlander_i2c_irq_enable(struct highlander_i2c_dev *dev)
iowrite16(ioread16(dev->base + SMCR) | SMCR_IEIC, dev->base + SMCR);
static inline void highlander_i2c_irq_disable(struct highlander_i2c_dev *dev)
iowrite16(ioread16(dev->base + SMCR) & ~SMCR_IEIC, dev->base + SMCR);
static inline void highlander_i2c_start(struct highlander_i2c_dev *dev)
iowrite16(ioread16(dev->base + SMCR) | SMCR_START, dev->base + SMCR);
static inline void highlander_i2c_done(struct highlander_i2c_dev *dev)
iowrite16(ioread16(dev->base + SMCR) | SMCR_IRIC, dev->base + SMCR);
static void highlander_i2c_setup(struct highlander_i2c_dev *dev)
u16 smmr;
smmr = ioread16(dev->base + SMMR);
smmr |= SMMR_TMMD;
if (iic_force_normal)
smmr &= ~SMMR_SP;
smmr |= SMMR_SP;
iowrite16(smmr, dev->base + SMMR);
static void smbus_write_data(u8 *src, u16 *dst, int len)
for (; len > 1; len -= 2) {
*dst++ = be16_to_cpup((u16 *)src);
src += 2;
if (len)
*dst = *src << 8;
static void smbus_read_data(u16 *src, u8 *dst, int len)
for (; len > 1; len -= 2) {
*(u16 *)dst = cpu_to_be16p(src++);
dst += 2;
if (len)
*dst = *src >> 8;
static void highlander_i2c_command(struct highlander_i2c_dev *dev,
u8 command, int len)
unsigned int i;
u16 cmd = (command << 8) | command;
for (i = 0; i < len; i += 2) {
if (len - i == 1)
cmd = command << 8;
iowrite16(cmd, dev->base + SMSADR + i);
dev_dbg(dev->dev, "command data[%x] 0x%04x\n", i/2, cmd);
static int highlander_i2c_wait_for_bbsy(struct highlander_i2c_dev *dev)
unsigned long timeout;
timeout = jiffies + msecs_to_jiffies(iic_timeout);
while (ioread16(dev->base + SMCR) & SMCR_BBSY) {
if (time_after(jiffies, timeout)) {
dev_warn(dev->dev, "timeout waiting for bus ready\n");
return -ETIMEDOUT;
return 0;
static int highlander_i2c_reset(struct highlander_i2c_dev *dev)
iowrite16(ioread16(dev->base + SMCR) | SMCR_RST, dev->base + SMCR);
return highlander_i2c_wait_for_bbsy(dev);
static int highlander_i2c_wait_for_ack(struct highlander_i2c_dev *dev)
u16 tmp = ioread16(dev->base + SMCR);
if ((tmp & (SMCR_IRIC | SMCR_ACKE)) == SMCR_ACKE) {
dev_warn(dev->dev, "ack abnormality\n");
return highlander_i2c_reset(dev);
return 0;
static irqreturn_t highlander_i2c_irq(int irq, void *dev_id)
struct highlander_i2c_dev *dev = dev_id;
static void highlander_i2c_poll(struct highlander_i2c_dev *dev)
unsigned long timeout;
u16 smcr;
timeout = jiffies + msecs_to_jiffies(iic_timeout);
for (;;) {
smcr = ioread16(dev->base + SMCR);
* Don't bother checking ACKE here, this and the reset
* are handled in highlander_i2c_wait_xfer_done() when
* waiting for the ACK.
if (smcr & SMCR_IRIC)
if (time_after(jiffies, timeout))
dev_err(dev->dev, "polling timed out\n");
static inline int highlander_i2c_wait_xfer_done(struct highlander_i2c_dev *dev)
if (dev->irq)
/* busy looping, the IRQ of champions */
return highlander_i2c_wait_for_ack(dev);
static int highlander_i2c_read(struct highlander_i2c_dev *dev)
int i, cnt;
u16 data[16];
if (highlander_i2c_wait_for_bbsy(dev))
return -EAGAIN;
if (highlander_i2c_wait_xfer_done(dev)) {
dev_err(dev->dev, "Arbitration loss\n");
return -EAGAIN;
* The R0P7780LC0011RL FPGA needs a significant delay between
* data read cycles, otherwise the transciever gets confused and
* garbage is returned when the read is subsequently aborted.
* It is not sufficient to wait for BBSY.
* While this generally only applies to the older SH7780-based
* Highlanders, the same issue can be observed on SH7785 ones,
* albeit less frequently. SH7780-based Highlanders may need
* this to be as high as 1000 ms.
if (iic_read_delay && time_before(jiffies, dev->last_read_time +
msleep(jiffies_to_msecs((dev->last_read_time +
msecs_to_jiffies(iic_read_delay)) - jiffies));
cnt = (dev->buf_len + 1) >> 1;
for (i = 0; i < cnt; i++) {
data[i] = ioread16(dev->base + SMTRDR + (i * sizeof(u16)));
dev_dbg(dev->dev, "read data[%x] 0x%04x\n", i, data[i]);
smbus_read_data(data, dev->buf, dev->buf_len);
dev->last_read_time = jiffies;
return 0;