On Mon, Mar 25, 2019 at 03:01:21PM +0000, Peter Rosin wrote: > On 2019-03-22 20:38, Pradeep Srinivasan wrote: > > I have verified the changes on PCA 9541. May I know how you want the test results to be shared ? (newbie here; please bear with me) > > > > root@cumulus:/home/cumulus# dmesg| grep "pca9541" | grep -v "pmbus" > > [ 2.922288] pca9541 1-0070: registered master selector for I2C pca9541 > > > > root@cumulus:/home/cumulus# cat /sys/class/i2c-dev/i2c-1/device/1-0070/name > > pca9541 > > This only verifies that the probe works and that the chip is detected properly. > It says nothing about if it works to communicate with whatever is beyond the > PCA9541, and nothing on how the interaction with the "alien" other master > connected to the PCA9541 is working. I don't know how I want this to be tested, > but if you have a setup with a PCA9541 / PCA9641 I would assume that you > have some kind of need for those chips and that you at least could report > if basic xfers through them are working? I don't need to see actual commands > that you have executed, I'm much more interested in some summary of what > you did and what worked (or not). > > E.g. if you have an eeprom beyond the master selector, you could read from > it in a loop while doing something else from the alien master and check if > it all works as expected? Perhaps try to verify timing if there are stalls > and/or timeouts etc. Go wild! But if you don't know how or don't have the Something like that is what I did to test the original implementation: Access all chips behind the mux from both ends continuously. Let that run for an hour or so and declare it a success if there is no error. Usually, while the code was still buggy, errors would show up within minutes, if not seconds. Guenter > time, I'd be happy with a report on basic functionality (but a little bit > more than probe-ok would be nice though), because the code affecting the > PCA9541 is probably not broken subtly, it either works as it did before or > it doesn't work at all. And any problem with the PCA9641 side of things > will not be a regression and therefore not a big problem... > > Cheers, > Peter > > > I need to do the same on PCA 9641. If the above is sufficient, I will grab a switch with PCA 9641 and check if the driver works . > > > > > > Thanks > > Pradeep > > > > On Thu, Mar 7, 2019 at 1:16 PM Peter Rosin <peda@xxxxxxxxxx <mailto:peda@xxxxxxxxxx>> wrote: > > > > Hi! > > > > I should have read Kens code more carefully, before signing off on it... > > > > Review comments inline... > > > > On 2019-03-07 00:15, Peter Rosin wrote: > > > Heavily based on code from Ken Chen <chen.kenyy@xxxxxxxxxxxx <mailto:chen.kenyy@xxxxxxxxxxxx>>. > > > > > > Signed-off-by: Peter Rosin <peda@xxxxxxxxxx <mailto:peda@xxxxxxxxxx>> > > > --- > > > drivers/i2c/muxes/Kconfig | 6 +- > > > drivers/i2c/muxes/i2c-mux-pca9541.c | 137 ++++++++++++++++++++++++++++++++++-- > > > 2 files changed, 136 insertions(+), 7 deletions(-) > > > > > > diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig > > > index 52a4a922e7e6..8532841de5db 100644 > > > --- a/drivers/i2c/muxes/Kconfig > > > +++ b/drivers/i2c/muxes/Kconfig > > > @@ -55,10 +55,10 @@ config I2C_MUX_LTC4306 > > > will be called i2c-mux-ltc4306. > > > > > > config I2C_MUX_PCA9541 > > > - tristate "NXP PCA9541 I2C Master Selector" > > > + tristate "NXP PCA9541/PCA9641 I2C Master Selectors" > > > help > > > - If you say yes here you get support for the NXP PCA9541 > > > - I2C Master Selector. > > > + If you say yes here you get support for the NXP PCA9541/PCA9641 > > > + I2C Master Selectors. > > > > > > This driver can also be built as a module. If so, the module > > > will be called i2c-mux-pca9541. > > > diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c > > > index 5eb36e3223d5..5d4e0c92e978 100644 > > > --- a/drivers/i2c/muxes/i2c-mux-pca9541.c > > > +++ b/drivers/i2c/muxes/i2c-mux-pca9541.c > > > @@ -1,5 +1,5 @@ > > > /* > > > - * I2C multiplexer driver for PCA9541 bus master selector > > > + * I2C multiplexer driver for PCA9541/PCA9641 bus master selectors > > > * > > > * Copyright (c) 2010 Ericsson AB. > > > * > > > @@ -28,8 +28,8 @@ > > > #include <linux/slab.h> > > > > > > /* > > > - * The PCA9541 is a bus master selector. It supports two I2C masters connected > > > - * to a single slave bus. > > > + * The PCA9541 and PCA9641 are bus master selector. They support two I2C masters > > > + * connected to a single slave bus. > > > * > > > * Before each bus transaction, a master has to acquire bus ownership. After the > > > * transaction is complete, bus ownership has to be released. This fits well > > > @@ -63,6 +63,33 @@ > > > #define PCA9541_BUSON (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON) > > > #define PCA9541_MYBUS (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS) > > > > > > +#define PCA9641_ID 0x00 > > > +#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 > > > > This appears to be the same thing as PCA9641_TIME above. The > > register is called PCA9641_RT in my data sheet. > > > > > + > > > /* 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 */ > > > @@ -73,6 +100,7 @@ > > > > > > enum chip_name { > > > pca9541, > > > + pca9641, > > > }; > > > > > > struct chip_desc { > > > @@ -102,6 +130,21 @@ static bool pca9541_busoff(int ctl) > > > return (ctl & PCA9541_BUSON) == PCA9541_BUSON; > > > } > > > > > > +static bool pca9641_lock_grant(int ctl) > > > +{ > > > + return !!(ctl & PCA9641_CTL_LOCK_GRANT); > > > +} > > > + > > > +static bool pca9641_other_lock(int sts) > > > +{ > > > + return !!(sts & PCA9641_STS_OTHER_LOCK); > > > +} > > > + > > > +static bool pca9641_busoff(int ctl, int sts) > > > +{ > > > + return !pca9641_lock_grant(ctl) && !pca9641_other_lock(sts); > > > +} > > > + > > > /* > > > * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer() > > > * as they will try to lock the adapter a second time. > > > @@ -256,6 +299,86 @@ static int pca9541_arbitrate(struct i2c_client *client) > > > return 0; > > > } > > > > > > +/* Release bus. */ > > > +static void pca9641_release_bus(struct i2c_client *client) > > > +{ > > > + pca9541_reg_write(client, PCA9641_CONTROL, 0); > > > > Should this release bus function really "clobber" the control bits > > PCA9641_CTL_IDLE_TIMER_DIS, PCA9641_CTL_SMBUS_DIS, PCA9641_CTL_PRIORITY? > > Yes yes, the driver never sets these bits so they are likely zero. But > > the driver doesn't reset the chip either, so some bootstrap code might > > have configured those bits... > > > > Also related to bus release, since the driver does not touch the > > reserve time register, and then clears the above bits, the only way > > to release the bus is if everything continues to work and the above > > pca9641_release_bus is in fact happening. But if the kernel crashes > > while hogging the bus, and fails to come up, then the other master > > has no way of stealing the ownership. I really feel that the driver > > should make use of the timers so that the arbiter releases the bus > > automatically on catastrophic failure. But maybe I plain and simple > > just misunderstand the datasheet? > > > > > +} > > > + > > > +/* > > > + * 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 pca9541 *data = i2c_mux_priv(muxc); > > > + int reg_ctl, reg_sts; > > > + > > > + reg_ctl = pca9541_reg_read(client, PCA9641_CONTROL); > > > + if (reg_ctl < 0) > > > + return reg_ctl; > > > + reg_sts = pca9541_reg_read(client, PCA9641_STATUS); > > > + > > > + if (pca9641_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; > > > + pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl); > > > + reg_ctl = pca9541_reg_read(client, PCA9641_CONTROL); > > > + > > > + if (pca9641_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; > > > + pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl); > > > + data->select_timeout = SELECT_DELAY_SHORT; > > > + > > > + return 1; > > > + } > > > + > > > + /* > > > + * Other master requested ownership. > > > + * Set extra long timeout to give it time to acquire it. > > > + */ > > > + data->select_timeout = SELECT_DELAY_LONG * 2; > > > + > > > + return 0; > > > + } > > > + > > > + if (pca9641_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; > > > + pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl); > > > + > > > + return 1; > > > + } > > > + > > > + if (pca9641_other_lock(reg_sts)) { > > > + /* > > > + * Other master owns the bus. > > > + * If arbitration timeout has expired, force ownership. > > > + * Otherwise request it. > > > > This comment is stale. Reading the data sheet, I find no way to force > > ownership with the PCA9641 (as indicated above in the release_bus > > review comment). But I have only browsed the data sheet so I could > > easily be mistaken... > > > > [time passes] > > > > Ahhh, wait, it could reset the chip to get a new chance to get ownership. > > But that will reset all registers for the other master as well, since I > > read it as if the reset is chip-global and not master-local with minimal > > effects on the other master. So, a big hammer indeed. > > > > Cheers, > > Peter > > > > > + */ > > > + data->select_timeout = SELECT_DELAY_LONG; > > > + reg_ctl |= PCA9641_CTL_LOCK_REQ; > > > + pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl); > > > + } > > > + > > > + return 0; > > > +} > > > + > > > static int pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan) > > > { > > > struct pca9541 *data = i2c_mux_priv(muxc); > > > @@ -295,10 +418,15 @@ static const struct chip_desc chips[] = { > > > .arbitrate = pca9541_arbitrate, > > > .release_bus = pca9541_release_bus, > > > }, > > > + [pca9641] = { > > > + .arbitrate = pca9641_arbitrate, > > > + .release_bus = pca9641_release_bus, > > > + }, > > > }; > > > > > > static const struct i2c_device_id pca9541_id[] = { > > > { "pca9541", pca9541 }, > > > + { "pca9641", pca9641 }, > > > {} > > > }; > > > > > > @@ -307,6 +435,7 @@ MODULE_DEVICE_TABLE(i2c, pca9541_id); > > > #ifdef CONFIG_OF > > > static const struct of_device_id pca9541_of_match[] = { > > > { .compatible = "nxp,pca9541", .data = &chips[pca9541] }, > > > + { .compatible = "nxp,pca9641", .data = &chips[pca9641] }, > > > {} > > > }; > > > MODULE_DEVICE_TABLE(of, pca9541_of_match); > > > @@ -392,5 +521,5 @@ static struct i2c_driver pca9541_driver = { > > > module_i2c_driver(pca9541_driver); > > > > > > MODULE_AUTHOR("Guenter Roeck <linux@xxxxxxxxxxxx <mailto:linux@xxxxxxxxxxxx>>"); > > > -MODULE_DESCRIPTION("PCA9541 I2C master selector driver"); > > > +MODULE_DESCRIPTION("PCA9541/PCA9641 I2C master selector driver"); > > > MODULE_LICENSE("GPL v2"); > > > > > >
