[PATCH linux dev-4.13] drivers: i2c: master arbiter: create driver
Joel Stanley
joel at jms.id.au
Tue Mar 13 14:52:52 AEDT 2018
On Mon, Mar 12, 2018 at 5:10 PM, ChenKenYY 陳永營 TAO
<chen.kenyy at inventec.com> wrote:
> 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.
If you think that there is a good reason to do a separate
implementation, then we should submit your version upstream and add
that information to your commit message.
Cheers,
Joel
>
>
> 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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