* [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
@ 2018-03-19 11:38 ` Ken Chen
0 siblings, 0 replies; 8+ messages in thread
From: Ken Chen @ 2018-03-19 11:38 UTC (permalink / raw)
To: linux, wsa, peda, linux-i2c, linux-kernel; +Cc: Ken Chen, joel
Initial PCA9641 2 chennel I2C bus master arbiter
with separate implementation. It has probe issue
and difference device hehavior between PCA9541
and PCA9641 in original PCA9641 patch.
Signed-off-by: Ken Chen <chen.kenyy@inventec.com>
---
drivers/i2c/muxes/Kconfig | 9 +
drivers/i2c/muxes/Makefile | 1 +
drivers/i2c/muxes/i2c-mux-pca9641.c | 360 ++++++++++++++++++++++++++++++++++++
3 files changed, 370 insertions(+)
create mode 100644 drivers/i2c/muxes/i2c-mux-pca9641.c
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 52a4a92..f9c51b8 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 6d9d865..a229a1a 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -12,6 +12,7 @@ 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..bcf45c8
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-pca9641.c
@@ -0,0 +1,360 @@
+/*
+ * I2C demultiplexer driver for PCA9641 bus master demultiplexer
+ *
+ * Copyright (c) 2010 Ericsson AB.
+ *
+ * Author: Ken Chen <chen.kenyy@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 BIT(0)
+#define PCA9641_CTL_LOCK_GRANT BIT(1)
+#define PCA9641_CTL_BUS_CONNECT BIT(2)
+#define PCA9641_CTL_BUS_INIT BIT(3)
+#define PCA9641_CTL_SMBUS_SWRST BIT(4)
+#define PCA9641_CTL_IDLE_TIMER_DIS BIT(5)
+#define PCA9641_CTL_SMBUS_DIS BIT(6)
+#define PCA9641_CTL_PRIORITY BIT(7)
+
+#define PCA9641_STS_OTHER_LOCK BIT(0)
+#define PCA9641_STS_BUS_INIT_FAIL BIT(1)
+#define PCA9641_STS_BUS_HUNG BIT(2)
+#define PCA9641_STS_MBOX_EMPTY BIT(3)
+#define PCA9641_STS_MBOX_FULL BIT(4)
+#define PCA9641_STS_TEST_INT BIT(5)
+#define PCA9641_STS_SCL_IO BIT(6)
+#define PCA9641_STS_SDA_IO BIT(7)
+
+#define PCA9641_RES_TIME 0x03
+
+#define busoff(x, y) (!((x) & PCA9641_CTL_LOCK_GRANT) && \
+ !((y) & PCA9641_STS_OTHER_LOCK))
+#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)
+{
+ 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 (busoff(reg_ctl, reg_sts)) {
+ /*
+ * 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);
+ 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);
+ }
+ 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@inventec.com>");
+MODULE_DESCRIPTION("PCA9641 I2C master demultiplexer driver");
+MODULE_LICENSE("GPL v2");
--
2.9.3
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
@ 2018-03-19 11:38 ` Ken Chen
0 siblings, 0 replies; 8+ messages in thread
From: Ken Chen @ 2018-03-19 11:38 UTC (permalink / raw)
To: linux, wsa, peda, linux-i2c, linux-kernel; +Cc: Ken Chen, joel
Initial PCA9641 2 chennel I2C bus master arbiter
with separate implementation. It has probe issue
and difference device hehavior between PCA9541
and PCA9641 in original PCA9641 patch.
Signed-off-by: Ken Chen <chen.kenyy@inventec.com>
---
drivers/i2c/muxes/Kconfig | 9 +
drivers/i2c/muxes/Makefile | 1 +
drivers/i2c/muxes/i2c-mux-pca9641.c | 360 ++++++++++++++++++++++++++++++++++++
3 files changed, 370 insertions(+)
create mode 100644 drivers/i2c/muxes/i2c-mux-pca9641.c
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 52a4a92..f9c51b8 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 6d9d865..a229a1a 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -12,6 +12,7 @@ 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..bcf45c8
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-pca9641.c
@@ -0,0 +1,360 @@
+/*
+ * I2C demultiplexer driver for PCA9641 bus master demultiplexer
+ *
+ * Copyright (c) 2010 Ericsson AB.
+ *
+ * Author: Ken Chen <chen.kenyy@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 BIT(0)
+#define PCA9641_CTL_LOCK_GRANT BIT(1)
+#define PCA9641_CTL_BUS_CONNECT BIT(2)
+#define PCA9641_CTL_BUS_INIT BIT(3)
+#define PCA9641_CTL_SMBUS_SWRST BIT(4)
+#define PCA9641_CTL_IDLE_TIMER_DIS BIT(5)
+#define PCA9641_CTL_SMBUS_DIS BIT(6)
+#define PCA9641_CTL_PRIORITY BIT(7)
+
+#define PCA9641_STS_OTHER_LOCK BIT(0)
+#define PCA9641_STS_BUS_INIT_FAIL BIT(1)
+#define PCA9641_STS_BUS_HUNG BIT(2)
+#define PCA9641_STS_MBOX_EMPTY BIT(3)
+#define PCA9641_STS_MBOX_FULL BIT(4)
+#define PCA9641_STS_TEST_INT BIT(5)
+#define PCA9641_STS_SCL_IO BIT(6)
+#define PCA9641_STS_SDA_IO BIT(7)
+
+#define PCA9641_RES_TIME 0x03
+
+#define busoff(x, y) (!((x) & PCA9641_CTL_LOCK_GRANT) && \
+ !((y) & PCA9641_STS_OTHER_LOCK))
+#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)
+{
+ 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 (busoff(reg_ctl, reg_sts)) {
+ /*
+ * 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);
+ 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);
+ }
+ 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@inventec.com>");
+MODULE_DESCRIPTION("PCA9641 I2C master demultiplexer driver");
+MODULE_LICENSE("GPL v2");
--
2.9.3
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
2018-03-19 11:38 ` Ken Chen
(?)
@ 2018-03-19 12:45 ` Peter Rosin
2018-03-19 13:44 ` Guenter Roeck
-1 siblings, 1 reply; 8+ messages in thread
From: Peter Rosin @ 2018-03-19 12:45 UTC (permalink / raw)
To: Ken Chen, linux, wsa, linux-i2c, linux-kernel; +Cc: joel
Hi Ken,
Thanks for the patch!
I would have liked this subject:
i2c: muxes: pca9641: new driver
On 2018-03-19 12:38, Ken Chen wrote:
> Initial PCA9641 2 chennel I2C bus master arbiter
channel
> with separate implementation. It has probe issue
> and difference device hehavior between PCA9541
behavior
> and PCA9641 in original PCA9641 patch.
>
> Signed-off-by: Ken Chen <chen.kenyy@inventec.com>
> ---
> drivers/i2c/muxes/Kconfig | 9 +
> drivers/i2c/muxes/Makefile | 1 +
> drivers/i2c/muxes/i2c-mux-pca9641.c | 360 ++++++++++++++++++++++++++++++++++++
Given the big similarities between this and the pca9541 driver,
I would very much prefer if you could extend that driver instead
of making an almost-copy like this.
I have added some comments below anyway, but most of them are
irrelevant given that I want this merged with the pca9541 driver.
But maybe Guenter feels differently about that merge?
> 3 files changed, 370 insertions(+)
> create mode 100644 drivers/i2c/muxes/i2c-mux-pca9641.c
>
> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
> index 52a4a92..f9c51b8 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 6d9d865..a229a1a 100644
> --- a/drivers/i2c/muxes/Makefile
> +++ b/drivers/i2c/muxes/Makefile
> @@ -12,6 +12,7 @@ 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..bcf45c8
> --- /dev/null
> +++ b/drivers/i2c/muxes/i2c-mux-pca9641.c
> @@ -0,0 +1,360 @@
> +/*
> + * I2C demultiplexer driver for PCA9641 bus master demultiplexer
> + *
> + * Copyright (c) 2010 Ericsson AB.
> + *
> + * Author: Ken Chen <chen.kenyy@inventec.com>
A bit rich to claim to be the sole author, when you clearly "just"
modified the pca9541 driver. Please state the history!
> + *
> + * Derived from:
Maybe you intended to add something here, but forgot?
> + *
> + * 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>
What is this last include for? We have moved away from specifying platform
data in (new) code.
> +
> +/*
> + * The PCA9641 is two I2C bus masters demultiplexer. It supports two I2C masters
"is two I2C bus masters" -> "is a two I2C bus master"
> + * 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
winner
> + * 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 BIT(0)
> +#define PCA9641_CTL_LOCK_GRANT BIT(1)
> +#define PCA9641_CTL_BUS_CONNECT BIT(2)
> +#define PCA9641_CTL_BUS_INIT BIT(3)
> +#define PCA9641_CTL_SMBUS_SWRST BIT(4)
> +#define PCA9641_CTL_IDLE_TIMER_DIS BIT(5)
> +#define PCA9641_CTL_SMBUS_DIS BIT(6)
> +#define PCA9641_CTL_PRIORITY BIT(7)
> +
> +#define PCA9641_STS_OTHER_LOCK BIT(0)
> +#define PCA9641_STS_BUS_INIT_FAIL BIT(1)
> +#define PCA9641_STS_BUS_HUNG BIT(2)
> +#define PCA9641_STS_MBOX_EMPTY BIT(3)
> +#define PCA9641_STS_MBOX_FULL BIT(4)
> +#define PCA9641_STS_TEST_INT BIT(5)
> +#define PCA9641_STS_SCL_IO BIT(6)
> +#define PCA9641_STS_SDA_IO BIT(7)
> +
> +#define PCA9641_RES_TIME 0x03
> +
> +#define busoff(x, y) (!((x) & PCA9641_CTL_LOCK_GRANT) && \
> + !((y) & PCA9641_STS_OTHER_LOCK))
> +#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" },
You need to describe the DT binding in Documentation/devicetree/bindings/i2c
See nxp,pca9541.txt for inspiration.
> + {}
> +};
> +#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)
> +{
> + 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 (busoff(reg_ctl, reg_sts)) {
> + /*
> + * 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);
> + 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);
> + }
> + 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;
Reading the data sheet, I noticed that the chip supports I2C device id.
There's a brand new function available in -next [1] that allows you to
check this. See the pca954x driver in -next for an example [2]. It checks
the I2C device id for the newer pca984x chips.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/i2c-core-base.c
i2c_get_device_id(), currently circa line 2000
[2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/muxes/i2c-mux-pca954x.c
> + /*
> + * 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),
Why 8? Should be 1, no?
> + 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);
> +
> +
Lose one of the empty lines here.
> + ret = i2c_mux_add_adapter(muxc, force, 0, 0);
> + if (ret) {
> + dev_err(&client->dev, "failed to register master demultiplexer\n");
This dev_err should go. i2c_mux_add_adapter provides a more
detailed error message on failure.
Cheers,
Peter
> + 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@inventec.com>");
> +MODULE_DESCRIPTION("PCA9641 I2C master demultiplexer driver");
> +MODULE_LICENSE("GPL v2");
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
2018-03-19 12:45 ` Peter Rosin
@ 2018-03-19 13:44 ` Guenter Roeck
2018-03-20 6:14 ` ChenKenYY 陳永營 TAO
0 siblings, 1 reply; 8+ messages in thread
From: Guenter Roeck @ 2018-03-19 13:44 UTC (permalink / raw)
To: Peter Rosin, Ken Chen, wsa, linux-i2c, linux-kernel; +Cc: joel
On 03/19/2018 05:45 AM, Peter Rosin wrote:
> Hi Ken,
>
> Thanks for the patch!
>
> I would have liked this subject:
> i2c: muxes: pca9641: new driver
>
> On 2018-03-19 12:38, Ken Chen wrote:
>> Initial PCA9641 2 chennel I2C bus master arbiter
>
> channel
>
>> with separate implementation. It has probe issue
>> and difference device hehavior between PCA9541
>
> behavior
>
>> and PCA9641 in original PCA9641 patch.
>>
>> Signed-off-by: Ken Chen <chen.kenyy@inventec.com>
>> ---
>> drivers/i2c/muxes/Kconfig | 9 +
>> drivers/i2c/muxes/Makefile | 1 +
>> drivers/i2c/muxes/i2c-mux-pca9641.c | 360 ++++++++++++++++++++++++++++++++++++
>
> Given the big similarities between this and the pca9541 driver,
> I would very much prefer if you could extend that driver instead
> of making an almost-copy like this.
>
> I have added some comments below anyway, but most of them are
> irrelevant given that I want this merged with the pca9541 driver.
>
> But maybe Guenter feels differently about that merge?
>
Same here. I didn't do a line-by-line comparison, but the code looks very similar.
I did look into the probe function searching for differences after noticing
"It has probe issue ...", but the difference there must be quite subtle since
I didn't find it. The only real difference seems to be arbitration, but that can
easily be added to the original driver as chip specific functions.
>> 3 files changed, 370 insertions(+)
>> create mode 100644 drivers/i2c/muxes/i2c-mux-pca9641.c
>>
>> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
>> index 52a4a92..f9c51b8 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 6d9d865..a229a1a 100644
>> --- a/drivers/i2c/muxes/Makefile
>> +++ b/drivers/i2c/muxes/Makefile
>> @@ -12,6 +12,7 @@ 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..bcf45c8
>> --- /dev/null
>> +++ b/drivers/i2c/muxes/i2c-mux-pca9641.c
>> @@ -0,0 +1,360 @@
>> +/*
>> + * I2C demultiplexer driver for PCA9641 bus master demultiplexer
>> + *
>> + * Copyright (c) 2010 Ericsson AB.
>> + *
>> + * Author: Ken Chen <chen.kenyy@inventec.com>
>
> A bit rich to claim to be the sole author, when you clearly "just"
> modified the pca9541 driver. Please state the history!
>
And while retaining the original copyright.
>> + *
>> + * Derived from:
>
> Maybe you intended to add something here, but forgot?
>
>> + *
>> + * 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.
>> + */
New files should use the SPDX license identifier.
>> +
>> +#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>
>
> What is this last include for? We have moved away from specifying platform
> data in (new) code.
>
>> +
>> +/*
>> + * The PCA9641 is two I2C bus masters demultiplexer. It supports two I2C masters
>
> "is two I2C bus masters" -> "is a two I2C bus master"
>
>> + * 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
>
> winner
>
>> + * 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 BIT(0)
>> +#define PCA9641_CTL_LOCK_GRANT BIT(1)
>> +#define PCA9641_CTL_BUS_CONNECT BIT(2)
>> +#define PCA9641_CTL_BUS_INIT BIT(3)
>> +#define PCA9641_CTL_SMBUS_SWRST BIT(4)
>> +#define PCA9641_CTL_IDLE_TIMER_DIS BIT(5)
>> +#define PCA9641_CTL_SMBUS_DIS BIT(6)
>> +#define PCA9641_CTL_PRIORITY BIT(7)
>> +
>> +#define PCA9641_STS_OTHER_LOCK BIT(0)
>> +#define PCA9641_STS_BUS_INIT_FAIL BIT(1)
>> +#define PCA9641_STS_BUS_HUNG BIT(2)
>> +#define PCA9641_STS_MBOX_EMPTY BIT(3)
>> +#define PCA9641_STS_MBOX_FULL BIT(4)
>> +#define PCA9641_STS_TEST_INT BIT(5)
>> +#define PCA9641_STS_SCL_IO BIT(6)
>> +#define PCA9641_STS_SDA_IO BIT(7)
>> +
>> +#define PCA9641_RES_TIME 0x03
>> +
>> +#define busoff(x, y) (!((x) & PCA9641_CTL_LOCK_GRANT) && \
>> + !((y) & PCA9641_STS_OTHER_LOCK))
>> +#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" },
>
> You need to describe the DT binding in Documentation/devicetree/bindings/i2c
> See nxp,pca9541.txt for inspiration.
>
>> + {}
>> +};
>> +#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)
>> +{
>> + 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 (busoff(reg_ctl, reg_sts)) {
>> + /*
>> + * 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);
>> + 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);
>> + }
>> + 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;
>
> Reading the data sheet, I noticed that the chip supports I2C device id.
> There's a brand new function available in -next [1] that allows you to
> check this. See the pca954x driver in -next for an example [2]. It checks
> the I2C device id for the newer pca984x chips.
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/i2c-core-base.c
> i2c_get_device_id(), currently circa line 2000
>
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/muxes/i2c-mux-pca954x.c
>
>> + /*
>> + * 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),
>
> Why 8? Should be 1, no?
>
>> + 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);
>> +
>> +
>
> Lose one of the empty lines here.
>
>> + ret = i2c_mux_add_adapter(muxc, force, 0, 0);
>> + if (ret) {
>> + dev_err(&client->dev, "failed to register master demultiplexer\n");
>
> This dev_err should go. i2c_mux_add_adapter provides a more
> detailed error message on failure.
>
> Cheers,
> Peter
>
>> + 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@inventec.com>");
>> +MODULE_DESCRIPTION("PCA9641 I2C master demultiplexer driver");
>> +MODULE_LICENSE("GPL v2");
>>
>
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
2018-03-19 13:44 ` Guenter Roeck
@ 2018-03-20 6:14 ` ChenKenYY 陳永營 TAO
0 siblings, 0 replies; 8+ messages in thread
From: ChenKenYY 陳永營 TAO @ 2018-03-20 6:14 UTC (permalink / raw)
To: Guenter Roeck; +Cc: Peter Rosin, wsa, linux-i2c, linux-kernel, Joel Stanley
Hi all,
I had merged into i2c-mux-pca9541.c
It will be send out later.
2018-03-19 21:44 GMT+08:00 Guenter Roeck <linux@roeck-us.net>:
> On 03/19/2018 05:45 AM, Peter Rosin wrote:
>>
>> Hi Ken,
>>
>> Thanks for the patch!
>>
>> I would have liked this subject:
>> i2c: muxes: pca9641: new driver
>>
>> On 2018-03-19 12:38, Ken Chen wrote:
>>>
>>> Initial PCA9641 2 chennel I2C bus master arbiter
>>
>>
>> channel
>>
>>> with separate implementation. It has probe issue
>>> and difference device hehavior between PCA9541
>>
>>
>> behavior
>>
>>> and PCA9641 in original PCA9641 patch.
>>>
>>> Signed-off-by: Ken Chen <chen.kenyy@inventec.com>
>>> ---
>>> drivers/i2c/muxes/Kconfig | 9 +
>>> drivers/i2c/muxes/Makefile | 1 +
>>> drivers/i2c/muxes/i2c-mux-pca9641.c | 360
>>> ++++++++++++++++++++++++++++++++++++
>>
>>
>> Given the big similarities between this and the pca9541 driver,
>> I would very much prefer if you could extend that driver instead
>> of making an almost-copy like this.
>>
>> I have added some comments below anyway, but most of them are
>> irrelevant given that I want this merged with the pca9541 driver.
>>
>> But maybe Guenter feels differently about that merge?
>>
>
> Same here. I didn't do a line-by-line comparison, but the code looks very
> similar.
> I did look into the probe function searching for differences after noticing
> "It has probe issue ...", but the difference there must be quite subtle
> since
> I didn't find it. The only real difference seems to be arbitration, but that
> can
> easily be added to the original driver as chip specific functions.
>
>
>>> 3 files changed, 370 insertions(+)
>>> create mode 100644 drivers/i2c/muxes/i2c-mux-pca9641.c
>>>
>>> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
>>> index 52a4a92..f9c51b8 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 6d9d865..a229a1a 100644
>>> --- a/drivers/i2c/muxes/Makefile
>>> +++ b/drivers/i2c/muxes/Makefile
>>> @@ -12,6 +12,7 @@ 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..bcf45c8
>>> --- /dev/null
>>> +++ b/drivers/i2c/muxes/i2c-mux-pca9641.c
>>> @@ -0,0 +1,360 @@
>>> +/*
>>> + * I2C demultiplexer driver for PCA9641 bus master demultiplexer
>>> + *
>>> + * Copyright (c) 2010 Ericsson AB.
>>> + *
>>> + * Author: Ken Chen <chen.kenyy@inventec.com>
>>
>>
>> A bit rich to claim to be the sole author, when you clearly "just"
>> modified the pca9541 driver. Please state the history!
>>
>
> And while retaining the original copyright.
>
>>> + *
>>> + * Derived from:
>>
>>
>> Maybe you intended to add something here, but forgot?
>>
>>> + *
>>> + * 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.
>>> + */
>
>
> New files should use the SPDX license identifier.
>
How can I use the SPDX license?
The previous license is GNU at i2c-mux-pca9541.c
>
>>> +
>>> +#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>
>>
>>
>> What is this last include for? We have moved away from specifying platform
>> data in (new) code.
Fixed
>>
>>> +
>>> +/*
>>> + * The PCA9641 is two I2C bus masters demultiplexer. It supports two I2C
>>> masters
>>
>>
>> "is two I2C bus masters" -> "is a two I2C bus master"
>>
>>> + * 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
>>
>>
>> winner
>>
>>> + * 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 BIT(0)
>>> +#define PCA9641_CTL_LOCK_GRANT BIT(1)
>>> +#define PCA9641_CTL_BUS_CONNECT BIT(2)
>>> +#define PCA9641_CTL_BUS_INIT BIT(3)
>>> +#define PCA9641_CTL_SMBUS_SWRST BIT(4)
>>> +#define PCA9641_CTL_IDLE_TIMER_DIS BIT(5)
>>> +#define PCA9641_CTL_SMBUS_DIS BIT(6)
>>> +#define PCA9641_CTL_PRIORITY BIT(7)
>>> +
>>> +#define PCA9641_STS_OTHER_LOCK BIT(0)
>>> +#define PCA9641_STS_BUS_INIT_FAIL BIT(1)
>>> +#define PCA9641_STS_BUS_HUNG BIT(2)
>>> +#define PCA9641_STS_MBOX_EMPTY BIT(3)
>>> +#define PCA9641_STS_MBOX_FULL BIT(4)
>>> +#define PCA9641_STS_TEST_INT BIT(5)
>>> +#define PCA9641_STS_SCL_IO BIT(6)
>>> +#define PCA9641_STS_SDA_IO BIT(7)
>>> +
>>> +#define PCA9641_RES_TIME 0x03
>>> +
>>> +#define busoff(x, y) (!((x) & PCA9641_CTL_LOCK_GRANT) && \
>>> + !((y) & PCA9641_STS_OTHER_LOCK))
>>> +#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" },
>>
>>
>> You need to describe the DT binding in
>> Documentation/devicetree/bindings/i2c
>> See nxp,pca9541.txt for inspiration.
>>
>>> + {}
>>> +};
>>> +#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)
>>> +{
>>> + 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 (busoff(reg_ctl, reg_sts)) {
>>> + /*
>>> + * 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);
>>> + 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);
>>> + }
>>> + 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;
>>
>>
>> Reading the data sheet, I noticed that the chip supports I2C device id.
>> There's a brand new function available in -next [1] that allows you to
>> check this. See the pca954x driver in -next for an example [2]. It checks
>> the I2C device id for the newer pca984x chips.
>>
>> [1]
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/i2c-core-base.c
>> i2c_get_device_id(), currently circa line 2000
>>
>> [2]
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/muxes/i2c-mux-pca954x.c
>>
Please help to review new patch the detect ID method.
>>> + /*
>>> + * 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),
>>
>>
>> Why 8? Should be 1, no?
Yes. should be 1.
>>
>>> + 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);
>>> +
>>> +
>>
>>
>> Lose one of the empty lines here.
Fix
>>
>>> + ret = i2c_mux_add_adapter(muxc, force, 0, 0);
>>> + if (ret) {
>>> + dev_err(&client->dev, "failed to register master
>>> demultiplexer\n");
>>
>>
>> This dev_err should go. i2c_mux_add_adapter provides a more
>> detailed error message on failure.
Removed and follow pca9541 probe code.
>>
>> Cheers,
>> Peter
>>
>>> + 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@inventec.com>");
>>> +MODULE_DESCRIPTION("PCA9641 I2C master demultiplexer driver");
>>> +MODULE_LICENSE("GPL v2");
>>>
>>
>>
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
@ 2018-03-20 6:14 ` ChenKenYY 陳永營 TAO
0 siblings, 0 replies; 8+ messages in thread
From: ChenKenYY 陳永營 TAO @ 2018-03-20 6:14 UTC (permalink / raw)
To: Guenter Roeck; +Cc: Peter Rosin, wsa, linux-i2c, linux-kernel, Joel Stanley
Hi all,
I had merged into i2c-mux-pca9541.c
It will be send out later.
2018-03-19 21:44 GMT+08:00 Guenter Roeck <linux@roeck-us.net>:
> On 03/19/2018 05:45 AM, Peter Rosin wrote:
>>
>> Hi Ken,
>>
>> Thanks for the patch!
>>
>> I would have liked this subject:
>> i2c: muxes: pca9641: new driver
>>
>> On 2018-03-19 12:38, Ken Chen wrote:
>>>
>>> Initial PCA9641 2 chennel I2C bus master arbiter
>>
>>
>> channel
>>
>>> with separate implementation. It has probe issue
>>> and difference device hehavior between PCA9541
>>
>>
>> behavior
>>
>>> and PCA9641 in original PCA9641 patch.
>>>
>>> Signed-off-by: Ken Chen <chen.kenyy@inventec.com>
>>> ---
>>> drivers/i2c/muxes/Kconfig | 9 +
>>> drivers/i2c/muxes/Makefile | 1 +
>>> drivers/i2c/muxes/i2c-mux-pca9641.c | 360
>>> ++++++++++++++++++++++++++++++++++++
>>
>>
>> Given the big similarities between this and the pca9541 driver,
>> I would very much prefer if you could extend that driver instead
>> of making an almost-copy like this.
>>
>> I have added some comments below anyway, but most of them are
>> irrelevant given that I want this merged with the pca9541 driver.
>>
>> But maybe Guenter feels differently about that merge?
>>
>
> Same here. I didn't do a line-by-line comparison, but the code looks very
> similar.
> I did look into the probe function searching for differences after noticing
> "It has probe issue ...", but the difference there must be quite subtle
> since
> I didn't find it. The only real difference seems to be arbitration, but that
> can
> easily be added to the original driver as chip specific functions.
>
>
>>> 3 files changed, 370 insertions(+)
>>> create mode 100644 drivers/i2c/muxes/i2c-mux-pca9641.c
>>>
>>> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
>>> index 52a4a92..f9c51b8 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 6d9d865..a229a1a 100644
>>> --- a/drivers/i2c/muxes/Makefile
>>> +++ b/drivers/i2c/muxes/Makefile
>>> @@ -12,6 +12,7 @@ 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..bcf45c8
>>> --- /dev/null
>>> +++ b/drivers/i2c/muxes/i2c-mux-pca9641.c
>>> @@ -0,0 +1,360 @@
>>> +/*
>>> + * I2C demultiplexer driver for PCA9641 bus master demultiplexer
>>> + *
>>> + * Copyright (c) 2010 Ericsson AB.
>>> + *
>>> + * Author: Ken Chen <chen.kenyy@inventec.com>
>>
>>
>> A bit rich to claim to be the sole author, when you clearly "just"
>> modified the pca9541 driver. Please state the history!
>>
>
> And while retaining the original copyright.
>
>>> + *
>>> + * Derived from:
>>
>>
>> Maybe you intended to add something here, but forgot?
>>
>>> + *
>>> + * 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.
>>> + */
>
>
> New files should use the SPDX license identifier.
>
How can I use the SPDX license?
The previous license is GNU at i2c-mux-pca9541.c
>
>>> +
>>> +#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>
>>
>>
>> What is this last include for? We have moved away from specifying platform
>> data in (new) code.
Fixed
>>
>>> +
>>> +/*
>>> + * The PCA9641 is two I2C bus masters demultiplexer. It supports two I2C
>>> masters
>>
>>
>> "is two I2C bus masters" -> "is a two I2C bus master"
>>
>>> + * 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
>>
>>
>> winner
>>
>>> + * 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 BIT(0)
>>> +#define PCA9641_CTL_LOCK_GRANT BIT(1)
>>> +#define PCA9641_CTL_BUS_CONNECT BIT(2)
>>> +#define PCA9641_CTL_BUS_INIT BIT(3)
>>> +#define PCA9641_CTL_SMBUS_SWRST BIT(4)
>>> +#define PCA9641_CTL_IDLE_TIMER_DIS BIT(5)
>>> +#define PCA9641_CTL_SMBUS_DIS BIT(6)
>>> +#define PCA9641_CTL_PRIORITY BIT(7)
>>> +
>>> +#define PCA9641_STS_OTHER_LOCK BIT(0)
>>> +#define PCA9641_STS_BUS_INIT_FAIL BIT(1)
>>> +#define PCA9641_STS_BUS_HUNG BIT(2)
>>> +#define PCA9641_STS_MBOX_EMPTY BIT(3)
>>> +#define PCA9641_STS_MBOX_FULL BIT(4)
>>> +#define PCA9641_STS_TEST_INT BIT(5)
>>> +#define PCA9641_STS_SCL_IO BIT(6)
>>> +#define PCA9641_STS_SDA_IO BIT(7)
>>> +
>>> +#define PCA9641_RES_TIME 0x03
>>> +
>>> +#define busoff(x, y) (!((x) & PCA9641_CTL_LOCK_GRANT) && \
>>> + !((y) & PCA9641_STS_OTHER_LOCK))
>>> +#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" },
>>
>>
>> You need to describe the DT binding in
>> Documentation/devicetree/bindings/i2c
>> See nxp,pca9541.txt for inspiration.
>>
>>> + {}
>>> +};
>>> +#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)
>>> +{
>>> + 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 (busoff(reg_ctl, reg_sts)) {
>>> + /*
>>> + * 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);
>>> + 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);
>>> + }
>>> + 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;
>>
>>
>> Reading the data sheet, I noticed that the chip supports I2C device id.
>> There's a brand new function available in -next [1] that allows you to
>> check this. See the pca954x driver in -next for an example [2]. It checks
>> the I2C device id for the newer pca984x chips.
>>
>> [1]
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/i2c-core-base.c
>> i2c_get_device_id(), currently circa line 2000
>>
>> [2]
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/i2c/muxes/i2c-mux-pca954x.c
>>
Please help to review new patch the detect ID method.
>>> + /*
>>> + * 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),
>>
>>
>> Why 8? Should be 1, no?
Yes. should be 1.
>>
>>> + 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);
>>> +
>>> +
>>
>>
>> Lose one of the empty lines here.
Fix
>>
>>> + ret = i2c_mux_add_adapter(muxc, force, 0, 0);
>>> + if (ret) {
>>> + dev_err(&client->dev, "failed to register master
>>> demultiplexer\n");
>>
>>
>> This dev_err should go. i2c_mux_add_adapter provides a more
>> detailed error message on failure.
Removed and follow pca9541 probe code.
>>
>> Cheers,
>> Peter
>>
>>> + 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@inventec.com>");
>>> +MODULE_DESCRIPTION("PCA9641 I2C master demultiplexer driver");
>>> +MODULE_LICENSE("GPL v2");
>>>
>>
>>
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
2018-03-19 11:38 ` Ken Chen
@ 2018-03-20 7:00 ` kbuild test robot
-1 siblings, 0 replies; 8+ messages in thread
From: kbuild test robot @ 2018-03-20 7:00 UTC (permalink / raw)
To: Ken Chen
Cc: kbuild-all, linux, wsa, peda, linux-i2c, linux-kernel, Ken Chen, joel
[-- Attachment #1: Type: text/plain, Size: 1067 bytes --]
Hi Ken,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on v4.16-rc4]
[also build test ERROR on next-20180319]
[cannot apply to linux/master]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Ken-Chen/drivers-i2c-master-arbiter-create-driver/20180320-134925
config: i386-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All errors (new ones prefixed by >>):
>> drivers/i2c/muxes/i2c-mux-pca9641.c:23:10: fatal error: linux/i2c/pca954x.h: No such file or directory
#include <linux/i2c/pca954x.h>
^~~~~~~~~~~~~~~~~~~~~
compilation terminated.
vim +23 drivers/i2c/muxes/i2c-mux-pca9641.c
22
> 23 #include <linux/i2c/pca954x.h>
24
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 63088 bytes --]
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver
@ 2018-03-20 7:00 ` kbuild test robot
0 siblings, 0 replies; 8+ messages in thread
From: kbuild test robot @ 2018-03-20 7:00 UTC (permalink / raw)
Cc: kbuild-all, linux, wsa, peda, linux-i2c, linux-kernel, Ken Chen, joel
[-- Attachment #1: Type: text/plain, Size: 1067 bytes --]
Hi Ken,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on v4.16-rc4]
[also build test ERROR on next-20180319]
[cannot apply to linux/master]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Ken-Chen/drivers-i2c-master-arbiter-create-driver/20180320-134925
config: i386-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All errors (new ones prefixed by >>):
>> drivers/i2c/muxes/i2c-mux-pca9641.c:23:10: fatal error: linux/i2c/pca954x.h: No such file or directory
#include <linux/i2c/pca954x.h>
^~~~~~~~~~~~~~~~~~~~~
compilation terminated.
vim +23 drivers/i2c/muxes/i2c-mux-pca9641.c
22
> 23 #include <linux/i2c/pca954x.h>
24
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 63088 bytes --]
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2018-03-20 7:00 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-03-19 11:38 [PATCH linux dev-4.16] drivers: i2c: master arbiter: create driver Ken Chen
2018-03-19 11:38 ` Ken Chen
2018-03-19 12:45 ` Peter Rosin
2018-03-19 13:44 ` Guenter Roeck
2018-03-20 6:14 ` ChenKenYY 陳永營 TAO
2018-03-20 6:14 ` ChenKenYY 陳永營 TAO
2018-03-20 7:00 ` kbuild test robot
2018-03-20 7:00 ` kbuild test robot
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