| Message ID | 20170516112758.2842-1-wsa+renesas@sang-engineering.com |
|---|---|
| State | RFC |
| Headers | show |
Hi Wolfram, On Tue, 16 May 2017 13:27:58 +0200, Wolfram Sang wrote: > This patch makes the stub driver parse the device tree when booting and > create a virtual bus with the desired devices attached. Here is an > example DTS snipplet making use of it. It is for simulating a more > complex camera device which has dependencies which needs to be sorted > out at boot time: > > i2c@42 { > compatible = "i2c-stub"; > > #address-cells = <1>; > #size-cells = <0>; > > des@4c { > compatible = "maxim,max9268"; > reg = <0x4c>; > }; > > eeprom@57 { > compatible = "atmel,24c02"; > reg = <0x57>; > }; > }; I get the idea and I understand the need to emulate the devices early in the boot process. However, how do you deal with the I2C devices pre-initialization (setting initial register values)? This is typically done in user-space with the i2c-stub-from-dump script, or manual calls to i2cset, but that would be too late in your case, wouldn't it? > > FIXME: can fw_* calls be used instead of of_*? > > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> > --- > > It was really useful when developing. When using fw_* calls, we probably could > make use of it with ACPI as well. Still, calling for opinions if we want this > upstream or if we want to stay module-only? Also, the binding should really > be marked as "development only". Or is it better to keep it as a separate > patch to keep the binding un-official? Code looks sane, but I can't comment on the bindings side of things as this isn't my area.
Hi Jean, > I get the idea and I understand the need to emulate the devices early > in the boot process. However, how do you deal with the I2C devices > pre-initialization (setting initial register values)? This is typically > done in user-space with the i2c-stub-from-dump script, or manual calls > to i2cset, but that would be too late in your case, wouldn't it? Yes. In my case, all 0 memory is fine. I needed to check writes which were enabling "channels" allowing me to do further initialization. I see the point, though, that we likely want to address your question before going upstream. > Code looks sane, but I can't comment on the bindings side of things as > this isn't my area. Sure, thanks for checking the code! Regards, Wolfram
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index efc3354d60ae89..6d38b38632f44c 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -99,7 +99,7 @@ source drivers/i2c/busses/Kconfig config I2C_STUB tristate "I2C/SMBus Test Stub" - depends on m + depends on m || OF default 'n' help This module may be useful to developers of SMBus client drivers, diff --git a/drivers/i2c/i2c-stub.c b/drivers/i2c/i2c-stub.c index 5627b1df391c7e..ce30bc4ac15a28 100644 --- a/drivers/i2c/i2c-stub.c +++ b/drivers/i2c/i2c-stub.c @@ -359,10 +359,44 @@ static void i2c_stub_free(void) kfree(stub_chips); } +#ifdef CONFIG_OF +void i2c_stub_parse_of(void) +{ + struct device_node *np, *child; + u32 reg, i = 0; + + np = of_find_compatible_node(NULL, NULL, "i2c-stub"); + if (!np) + return; + + for_each_available_child_of_node(np, child) { + if (of_property_read_u32(child, "reg", ®) == 0) { + chip_addr[i++] = reg; + if (i == MAX_CHIPS) { + pr_warn("Maximum number of chips reached!\n"); + break; + } + } + } + + stub_adapter.dev.of_node = np; + + np = of_find_compatible_node(np, NULL, "i2c-stub"); + if (np) { + pr_warn("Driver can currently do only one stub from DT!\n"); + of_node_put(np); + } +} +#else +void i2c_stub_parse_of(void) { } +#endif + static int __init i2c_stub_init(void) { int i, ret; + i2c_stub_parse_of(); + if (!chip_addr[0]) { pr_err("Please specify a chip address\n"); return -ENODEV;
This patch makes the stub driver parse the device tree when booting and create a virtual bus with the desired devices attached. Here is an example DTS snipplet making use of it. It is for simulating a more complex camera device which has dependencies which needs to be sorted out at boot time: i2c@42 { compatible = "i2c-stub"; #address-cells = <1>; #size-cells = <0>; des@4c { compatible = "maxim,max9268"; reg = <0x4c>; }; eeprom@57 { compatible = "atmel,24c02"; reg = <0x57>; }; }; FIXME: can fw_* calls be used instead of of_*? Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- It was really useful when developing. When using fw_* calls, we probably could make use of it with ACPI as well. Still, calling for opinions if we want this upstream or if we want to stay module-only? Also, the binding should really be marked as "development only". Or is it better to keep it as a separate patch to keep the binding un-official? drivers/i2c/Kconfig | 2 +- drivers/i2c/i2c-stub.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+), 1 deletion(-)