[PATCH linux dev-4.13] drivers: i2c: master arbiter: create driver
ChenKenYY 陳永營 TAO
chen.kenyy at inventec.com
Thu Mar 8 16:06:45 AEDT 2018
Hi Joel,
Sure, I can take it, but I need some instructions on the next action.
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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