[PATCH linux dev-4.13] drivers: i2c: master arbiter: create driver
ChenKenYY 陳永營 TAO
chen.kenyy at inventec.com
Mon Mar 12 17:40:29 AEDT 2018
Hi Joel,
Could I use an independent .c file(PCA9641) to upstream this driver?
Because the reference code has probe issue and sperate the difference
device behavior between PCA9541 and PCA9641 by function.
So I think It would be better using an independent .c file.
Best Regards,
Ken
2018-03-08 13:34 GMT+08:00 Joel Stanley <joel at jms.id.au>:
> On Thu, Mar 8, 2018 at 3:36 PM, ChenKenYY 陳永營 TAO
> <chen.kenyy at inventec.com> wrote:
>> Hi Joel,
>>
>> Sure, I can take it, but I need some instructions on the next action.
>
> Okay. I suggest you download the patch from patchwork and apply it to
> the latest kernel release, 4.16-rc4:
>
> https://patchwork.ozlabs.org/patch/726491/
>
> You can download it by clicking the 'mbox' link at the top right of the page.
>
> Now you will have a file called
> RFC-i2c-mux-Driver-for-PCA9641-I2C-Master-Arbiter.patch.
>
> $ git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> $ cd linux
> $ git checkout -b pca9641-mux v4.16-rc4
> $ git am ~/Downloads/RFC-i2c-mux-Driver-for-PCA9641-I2C-Master-Arbiter.patch
>
>
> From there, take a look at the comments on the two reviews that Vidya had:
>
> https://patchwork.ozlabs.org/patch/726491/#1580479
> https://patchwork.ozlabs.org/patch/726491/#1582916
>
> Fix those issues, and add your signed off by:
>
> $ git add drivers/i2c/muxes/i2c-mux-pca9541.c
> $ git commit --amend -s
>
> Then test this driver on your board. To do this, modify the device
> tree. You should be able to do this by modifying the ast2500-evb
> device tree, and boot that on your system.
>
> Once this is working, use the checkpatch.pl tool to check for common mistakes:
>
> $ ./scripts/checkpatch.pl drivers/i2c/muxes/i2c-mux-pca9541.c
>
> Then use get_maintainer.pl to get a list of people you should send the patch to:
>
> $ ./scripts/get_maintainer.pl -f drivers/i2c/muxes/i2c-mux-pca9541.c
> Guenter Roeck <linux at roeck-us.net> (maintainer:PCA9541 I2C BUS MASTER
> SELECTOR DRIVER)
> Peter Rosin <peda at axentia.se> (maintainer:I2C MUXES)
> Wolfram Sang <wsa at the-dreams.de> (maintainer:I2C SUBSYSTEM)
> linux-i2c at vger.kernel.org (open list:PCA9541 I2C BUS MASTER SELECTOR DRIVER)
> linux-kernel at vger.kernel.org (open list)
>
> In addition, please add me to this list so I can help. Then send the
> patch out, with a comment in the commit message (below the ---) that
> you have continued this work from the previous author, and have tested
> it on your system.
>
> Cheers,
>
> Joel
>
>>
>> Thanks,
>> Ken
>>
>> 2018-03-08 11:02 GMT+08:00 Joel Stanley <joel at jms.id.au>:
>>> Hello Ken,
>>>
>>> On Fri, Feb 23, 2018 at 3:52 PM, Ken Chen <chen.kenyy at inventec.com> wrote:
>>>> Initial PCA9641 2 chennel I2C bus master arbiter
>>>>
>>>> Signed-off-by: Ken Chen <chen.kenyy at inventec.com>
>>>
>>> The code here looks good. I did some searching, and found that someone
>>> submitted a driver for this part about a year ago:
>>>
>>> https://patchwork.ozlabs.org/patch/726491/
>>>
>>> Unfortunately the submitter did not send another version after it was
>>> reviewed. I suggest we take up the patch that was submitted, make the
>>> changes suggested, and submit it upstream. Are you able to take on
>>> that work?
>>>
>>> Cheers,
>>>
>>> Joel
>>>
>>>> ---
>>>> drivers/i2c/muxes/Kconfig | 9 +
>>>> drivers/i2c/muxes/Makefile | 1 +
>>>> drivers/i2c/muxes/i2c-mux-pca9641.c | 372 ++++++++++++++++++++++++++++++++++++
>>>> 3 files changed, 382 insertions(+)
>>>> create mode 100644 drivers/i2c/muxes/i2c-mux-pca9641.c
>>>>
>>>> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
>>>> index 1712132..1cd1ad3 100644
>>>> --- a/drivers/i2c/muxes/Kconfig
>>>> +++ b/drivers/i2c/muxes/Kconfig
>>>> @@ -73,6 +73,15 @@ config I2C_MUX_PCA954x
>>>> This driver can also be built as a module. If so, the module
>>>> will be called i2c-mux-pca954x.
>>>>
>>>> +config I2C_MUX_PCA9641
>>>> + tristate "NXP PCA9641 I2C Master demultiplexer"
>>>> + help
>>>> + If you say yes here you get support for the NXP PCA9641
>>>> + I2C Master demultiplexer with an arbiter function.
>>>> +
>>>> + This driver can also be built as a module. If so, the module
>>>> + will be called i2c-mux-pca9641.
>>>> +
>>>> config I2C_MUX_PINCTRL
>>>> tristate "pinctrl-based I2C multiplexer"
>>>> depends on PINCTRL
>>>> diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
>>>> index 4a67d31..f95d5f5 100644
>>>> --- a/drivers/i2c/muxes/Makefile
>>>> +++ b/drivers/i2c/muxes/Makefile
>>>> @@ -11,6 +11,7 @@ obj-$(CONFIG_I2C_MUX_LTC4306) += i2c-mux-ltc4306.o
>>>> obj-$(CONFIG_I2C_MUX_MLXCPLD) += i2c-mux-mlxcpld.o
>>>> obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
>>>> obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
>>>> +obj-$(CONFIG_I2C_MUX_PCA9641) += i2c-mux-pca9641.o
>>>> obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
>>>> obj-$(CONFIG_I2C_MUX_REG) += i2c-mux-reg.o
>>>>
>>>> diff --git a/drivers/i2c/muxes/i2c-mux-pca9641.c b/drivers/i2c/muxes/i2c-mux-pca9641.c
>>>> new file mode 100644
>>>> index 0000000..ca7b816
>>>> --- /dev/null
>>>> +++ b/drivers/i2c/muxes/i2c-mux-pca9641.c
>>>> @@ -0,0 +1,372 @@
>>>> +/*
>>>> + * I2C demultiplexer driver for PCA9641 bus master demultiplexer
>>>> + *
>>>> + * Copyright (c) 2010 Ericsson AB.
>>>> + *
>>>> + * Author: Ken Chen <chen.kenyy at inventec.com>
>>>> + *
>>>> + * Derived from:
>>>> + *
>>>> + * This file is licensed under the terms of the GNU General Public
>>>> + * License version 2. This program is licensed "as is" without any
>>>> + * warranty of any kind, whether express or implied.
>>>> + */
>>>> +
>>>> +#include <linux/module.h>
>>>> +#include <linux/jiffies.h>
>>>> +#include <linux/delay.h>
>>>> +#include <linux/slab.h>
>>>> +#include <linux/device.h>
>>>> +#include <linux/i2c.h>
>>>> +#include <linux/i2c-mux.h>
>>>> +
>>>> +#include <linux/i2c/pca954x.h>
>>>> +
>>>> +/*
>>>> + * The PCA9641 is two I2C bus masters demultiplexer. It supports two I2C masters
>>>> + * connected to a single slave bus.
>>>> + *
>>>> + * It is designed for high reliability dual master I2C bus applications where
>>>> + * correct system operation is required, even when two I2C master issue their
>>>> + * commands at the same time. The arbiter will select a winner and let it work
>>>> + * uninterrupted, and the losing master will take control of the I2C bus after
>>>> + * the winnter has finished. The arbiter also allows for queued requests where
>>>> + * a master requests the downstream bus while the other master has control.
>>>> + *
>>>> + */
>>>> +
>>>> +#define PCA9641_ID 0x01
>>>> +#define PCA9641_ID_MAGIC 0x38
>>>> +
>>>> +#define PCA9641_CONTROL 0x01
>>>> +#define PCA9641_STATUS 0x02
>>>> +#define PCA9641_TIME 0x03
>>>> +
>>>> +#define PCA9641_CTL_LOCK_REQ (1 << 0)
>>>> +#define PCA9641_CTL_LOCK_GRANT (1 << 1)
>>>> +#define PCA9641_CTL_BUS_CONNECT (1 << 2)
>>>> +#define PCA9641_CTL_BUS_INIT (1 << 3)
>>>> +#define PCA9641_CTL_SMBUS_SWRST (1 << 4)
>>>> +#define PCA9641_CTL_IDLE_TIMER_DIS (1 << 5)
>>>> +#define PCA9641_CTL_SMBUS_DIS (1 << 6)
>>>> +#define PCA9641_CTL_PRIORITY (1 << 7)
>>>> +
>>>> +#define PCA9641_STS_OTHER_LOCK (1 << 0)
>>>> +#define PCA9641_STS_BUS_INIT_FAIL (1 << 1)
>>>> +#define PCA9641_STS_BUS_HUNG (1 << 2)
>>>> +#define PCA9641_STS_MBOX_EMPTY (1 << 3)
>>>> +#define PCA9641_STS_MBOX_FULL (1 << 4)
>>>> +#define PCA9641_STS_TEST_INT (1 << 5)
>>>> +#define PCA9641_STS_SCL_IO (1 << 6)
>>>> +#define PCA9641_STS_SDA_IO (1 << 7)
>>>> +
>>>> +#define PCA9641_RES_TIME 0x03
>>>> +
>>>> +#define other_lock(x) ((x) & PCA9641_STS_OTHER_LOCK)
>>>> +#define lock_grant(x) ((x) & PCA9641_CTL_LOCK_GRANT)
>>>> +
>>>> +/* arbitration timeouts, in jiffies */
>>>> +#define ARB_TIMEOUT (HZ / 8) /* 125 ms until forcing bus ownership */
>>>> +#define ARB2_TIMEOUT (HZ / 4) /* 250 ms until acquisition failure */
>>>> +
>>>> +/* arbitration retry delays, in us */
>>>> +#define SELECT_DELAY_SHORT 50
>>>> +#define SELECT_DELAY_LONG 1000
>>>> +
>>>> +struct pca9641 {
>>>> + struct i2c_client *client;
>>>> + unsigned long select_timeout;
>>>> + unsigned long arb_timeout;
>>>> +};
>>>> +
>>>> +static const struct i2c_device_id pca9641_id[] = {
>>>> + {"pca9641", 0},
>>>> + {}
>>>> +};
>>>> +
>>>> +MODULE_DEVICE_TABLE(i2c, pca9641_id);
>>>> +
>>>> +#ifdef CONFIG_OF
>>>> +static const struct of_device_id pca9641_of_match[] = {
>>>> + { .compatible = "nxp,pca9641" },
>>>> + {}
>>>> +};
>>>> +#endif
>>>> +
>>>> +/*
>>>> + * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
>>>> + * as they will try to lock the adapter a second time.
>>>> + */
>>>> +static int pca9641_reg_write(struct i2c_client *client, u8 command, u8 val)
>>>> +{
>>>> + struct i2c_adapter *adap = client->adapter;
>>>> + int ret;
>>>> +
>>>> + if (adap->algo->master_xfer) {
>>>> + struct i2c_msg msg;
>>>> + char buf[2];
>>>> +
>>>> + msg.addr = client->addr;
>>>> + msg.flags = 0;
>>>> + msg.len = 2;
>>>> + buf[0] = command;
>>>> + buf[1] = val;
>>>> + msg.buf = buf;
>>>> + ret = __i2c_transfer(adap, &msg, 1);
>>>> + } else {
>>>> + union i2c_smbus_data data;
>>>> +
>>>> + data.byte = val;
>>>> + ret = adap->algo->smbus_xfer(adap, client->addr,
>>>> + client->flags,
>>>> + I2C_SMBUS_WRITE,
>>>> + command,
>>>> + I2C_SMBUS_BYTE_DATA, &data);
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +/*
>>>> + * Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
>>>> + * as they will try to lock adapter a second time.
>>>> + */
>>>> +static int pca9641_reg_read(struct i2c_client *client, u8 command)
>>>> +{
>>>> + struct i2c_adapter *adap = client->adapter;
>>>> + int ret;
>>>> + u8 val;
>>>> +
>>>> + if (adap->algo->master_xfer) {
>>>> + struct i2c_msg msg[2] = {
>>>> + {
>>>> + .addr = client->addr,
>>>> + .flags = 0,
>>>> + .len = 1,
>>>> + .buf = &command
>>>> + },
>>>> + {
>>>> + .addr = client->addr,
>>>> + .flags = I2C_M_RD,
>>>> + .len = 1,
>>>> + .buf = &val
>>>> + }
>>>> + };
>>>> + ret = __i2c_transfer(adap, msg, 2);
>>>> + if (ret == 2)
>>>> + ret = val;
>>>> + else if (ret >= 0)
>>>> + ret = -EIO;
>>>> + } else {
>>>> + union i2c_smbus_data data;
>>>> +
>>>> + ret = adap->algo->smbus_xfer(adap, client->addr,
>>>> + client->flags,
>>>> + I2C_SMBUS_READ,
>>>> + command,
>>>> + I2C_SMBUS_BYTE_DATA, &data);
>>>> + if (!ret)
>>>> + ret = data.byte;
>>>> + }
>>>> + return ret;
>>>> +}
>>>> +
>>>> +/*
>>>> + * Arbitration management functions
>>>> + */
>>>> +static void pca9641_release_bus(struct i2c_client *client)
>>>> +{
>>>> + int reg;
>>>> +
>>>> + pca9641_reg_write(client, PCA9641_CONTROL, 0);
>>>> +}
>>>> +
>>>> +/*
>>>> + * Channel arbitration
>>>> + *
>>>> + * Return values:
>>>> + * <0: error
>>>> + * 0 : bus not acquired
>>>> + * 1 : bus acquired
>>>> + */
>>>> +static int pca9641_arbitrate(struct i2c_client *client)
>>>> +{
>>>> + struct i2c_mux_core *muxc = i2c_get_clientdata(client);
>>>> + struct pca9641 *data = i2c_mux_priv(muxc);
>>>> + int reg_ctl, reg_sts;
>>>> +
>>>> + reg_ctl = pca9641_reg_read(client, PCA9641_CONTROL);
>>>> + if (reg_ctl < 0)
>>>> + return reg_ctl;
>>>> + reg_sts = pca9641_reg_read(client, PCA9641_STATUS);
>>>> +
>>>> + if (!other_lock(reg_sts) && !lock_grant(reg_ctl)) {
>>>> + /*
>>>> + * Bus is off. Request ownership or turn it on unless
>>>> + * other master requested ownership.
>>>> + */
>>>> + reg_ctl |= PCA9641_CTL_LOCK_REQ;
>>>> + pca9641_reg_write(client, PCA9641_CONTROL, reg_ctl);
>>>> +
>>>> + udelay(100);
>>>> +
>>>> + reg_ctl = pca9641_reg_read(client, PCA9641_CONTROL);
>>>> +
>>>> + if (lock_grant(reg_ctl)) {
>>>> + /*
>>>> + * Other master did not request ownership,
>>>> + * or arbitration timeout expired. Take the bus.
>>>> + */
>>>> + reg_ctl |= PCA9641_CTL_BUS_CONNECT | PCA9641_CTL_LOCK_REQ;
>>>> + pca9641_reg_write(client, PCA9641_CONTROL, reg_ctl);
>>>> + data->select_timeout = SELECT_DELAY_SHORT;
>>>> +
>>>> + return 1;
>>>> + } else {
>>>> + /*
>>>> + * Other master requested ownership.
>>>> + * Set extra long timeout to give it time to acquire it.
>>>> + */
>>>> + data->select_timeout = SELECT_DELAY_LONG * 2;
>>>> + }
>>>> + } else if (lock_grant(reg_ctl)) {
>>>> + /*
>>>> + * Bus is on, and we own it. We are done with acquisition.
>>>> + */
>>>> + reg_ctl |= PCA9641_CTL_BUS_CONNECT | PCA9641_CTL_LOCK_REQ;
>>>> + pca9641_reg_write(client, PCA9641_CONTROL, reg_ctl);
>>>> +
>>>> + return 1;
>>>> + } else if (other_lock(reg_sts)) {
>>>> + /*
>>>> + * Other master owns the bus.
>>>> + * If arbitration timeout has expired, force ownership.
>>>> + * Otherwise request it.
>>>> + */
>>>> + data->select_timeout = SELECT_DELAY_LONG;
>>>> + reg_ctl |= PCA9641_CTL_LOCK_REQ;
>>>> + pca9641_reg_write(client, PCA9641_CONTROL, reg_ctl);
>>>> +
>>>> + /*
>>>> + * if (time_is_before_eq_jiffies(data->arb_timeout)) {
>>>> + * TODO:Time is up, take the bus and reset it.
>>>> + *
>>>> + *} else {
>>>> + * TODO: Request bus ownership if needed
>>>> + *
>>>> + *}
>>>> + */
>>>> + }
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int pca9641_select_chan(struct i2c_mux_core *muxc, u32 chan)
>>>> +{
>>>> + struct pca9641 *data = i2c_mux_priv(muxc);
>>>> + struct i2c_client *client = data->client;
>>>> + int ret;
>>>> + unsigned long timeout = jiffies + ARB2_TIMEOUT;
>>>> + /* give up after this time */
>>>> +
>>>> + data->arb_timeout = jiffies + ARB_TIMEOUT;
>>>> + /* force bus ownership after this time */
>>>> +
>>>> + do {
>>>> + ret = pca9641_arbitrate(client);
>>>> + if (ret)
>>>> + return ret < 0 ? ret : 0;
>>>> +
>>>> + if (data->select_timeout == SELECT_DELAY_SHORT)
>>>> + udelay(data->select_timeout);
>>>> + else
>>>> + msleep(data->select_timeout / 1000);
>>>> + } while (time_is_after_eq_jiffies(timeout));
>>>> +
>>>> + return -ETIMEDOUT;
>>>> +}
>>>> +
>>>> +static int pca9641_release_chan(struct i2c_mux_core *muxc, u32 chan)
>>>> +{
>>>> + struct pca9641 *data = i2c_mux_priv(muxc);
>>>> + struct i2c_client *client = data->client;
>>>> +
>>>> + pca9641_release_bus(client);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +/*
>>>> + * I2C init/probing/exit functions
>>>> + */
>>>> +static int pca9641_probe(struct i2c_client *client,
>>>> + const struct i2c_device_id *id)
>>>> +{
>>>> + struct i2c_adapter *adap = client->adapter;
>>>> + struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
>>>> + struct i2c_mux_core *muxc;
>>>> + struct pca9641 *data;
>>>> + int force;
>>>> + int ret;
>>>> +
>>>> + if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
>>>> + return -ENODEV;
>>>> +
>>>> + /*
>>>> + * I2C accesses are unprotected here.
>>>> + * We have to lock the adapter before releasing the bus.
>>>> + */
>>>> + i2c_lock_adapter(adap);
>>>> + pca9641_release_bus(client);
>>>> + i2c_unlock_adapter(adap);
>>>> +
>>>> + /* Create mux adapter */
>>>> +
>>>> + force = 0;
>>>> + if (pdata)
>>>> + force = pdata->modes[0].adap_id;
>>>> + muxc = i2c_mux_alloc(adap, &client->dev, 8, sizeof(*data),
>>>> + I2C_MUX_ARBITRATOR,
>>>> + pca9641_select_chan, pca9641_release_chan);
>>>> + if (!muxc)
>>>> + return -ENOMEM;
>>>> +
>>>> + data = i2c_mux_priv(muxc);
>>>> + data->client = client;
>>>> +
>>>> + i2c_set_clientdata(client, muxc);
>>>> +
>>>> +
>>>> + ret = i2c_mux_add_adapter(muxc, force, 0, 0);
>>>> + if (ret) {
>>>> + dev_err(&client->dev, "failed to register master demultiplexer\n");
>>>> + return ret;
>>>> + }
>>>> +
>>>> + dev_info(&client->dev, "registered master demultiplexer for I2C %s\n",
>>>> + client->name);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int pca9641_remove(struct i2c_client *client)
>>>> +{
>>>> + struct i2c_mux_core *muxc = i2c_get_clientdata(client);
>>>> +
>>>> + i2c_mux_del_adapters(muxc);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static struct i2c_driver pca9641_driver = {
>>>> + .driver = {
>>>> + .name = "pca9641",
>>>> + .of_match_table = of_match_ptr(pca9641_of_match),
>>>> + },
>>>> + .probe = pca9641_probe,
>>>> + .remove = pca9641_remove,
>>>> + .id_table = pca9641_id,
>>>> +};
>>>> +
>>>> +module_i2c_driver(pca9641_driver);
>>>> +
>>>> +MODULE_AUTHOR("Ken Chen <chen.kenyy at inventec.com>");
>>>> +MODULE_DESCRIPTION("PCA9641 I2C master demultiplexer driver");
>>>> +MODULE_LICENSE("GPL v2");
>>>> --
>>>> 2.9.3
>>>>
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