On 03/12/12 12:11, the mail apparently from Ming Lei included:
On Mon, Dec 3, 2012 at 12:37 AM, Andy Green <andy.green@xxxxxxxxxx> wrote:
On 02/12/12 23:01, the mail apparently from Ming Lei included:
Hi -
This patch defines power controller for powering on/off LAN95xx
USB hub and USB ethernet devices, and implements one match function
to associate the power controller with related USB port device.
The big problem of this approach is that it depends on the global
device ADD/DEL notifier.
Another idea of associating power controller with port device
is by introducing usb port driver, and move all this port power
control stuff from platform code to the port driver, which is just
what I think of and looks doable. The problem of the idea is that
port driver is per board, so maybe cause lots of platform sort of
code to be put under drivers/usb/port/, but this approach can avoid
global device ADD/DEL notifier.
I'd like to get some feedback about which one is better or other choice,
then I may do it in next cycle.
Cc: Andy Green <andy.green@xxxxxxxxxx>
Cc: Roger Quadros <rogerq@xxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: Felipe Balbi <balbi@xxxxxx>
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
arch/arm/mach-omap2/board-omap4panda.c | 99
+++++++++++++++++++++++++++++++-
1 file changed, 96 insertions(+), 3 deletions(-)
diff --git a/arch/arm/mach-omap2/board-omap4panda.c
b/arch/arm/mach-omap2/board-omap4panda.c
index 5c8e9ce..3183832 100644
--- a/arch/arm/mach-omap2/board-omap4panda.c
+++ b/arch/arm/mach-omap2/board-omap4panda.c
@@ -32,6 +32,8 @@
#include <linux/usb/musb.h>
#include <linux/wl12xx.h>
#include <linux/platform_data/omap-abe-twl6040.h>
+#include <linux/power_controller.h>
+#include <linux/usb/port.h>
#include <asm/hardware/gic.h>
#include <asm/mach-types.h>
@@ -154,6 +156,99 @@ static struct gpio panda_ehci_gpios[] __initdata = {
{ GPIO_HUB_NRESET, GPIOF_OUT_INIT_LOW, "hub_nreset" },
};
+static void ehci_hub_power_on(struct power_controller *pc, struct device
*dev)
+{
+ gpio_set_value(GPIO_HUB_NRESET, 1);
+ gpio_set_value(GPIO_HUB_POWER, 1);
+}
You should wait a bit after applying power to the smsc chip before letting
go of nReset too. In the regulator-based implementation I sent it's handled
by delays encoded in the regulator structs.
It isn't a big thing about the discussion. If these code is only platform code,
we can use gpio or regulator or other thing.
Well, you need a delay there FYI. It's just a nit.
+static void ehci_hub_power_off(struct power_controller *pc, struct device
*dev)
+{
+ gpio_set_value(GPIO_HUB_NRESET, 0);
+ gpio_set_value(GPIO_HUB_POWER, 0);
+}
+
+static struct usb_port_power_switch_data root_hub_port_data = {
+ .hub_tier = 0,
+ .port_number = 1,
+ .type = USB_PORT_CONNECT_TYPE_HARD_WIRED,
+};
+
+static struct usb_port_power_switch_data smsc_hub_port_data = {
+ .hub_tier = 1,
+ .port_number = 1,
+ .type = USB_PORT_CONNECT_TYPE_HARD_WIRED,
+};
+
+static struct power_controller pc = {
+ .name = "omap_hub_eth_pc",
+ .count = ATOMIC_INIT(0),
+ .power_on = ehci_hub_power_on,
+ .power_off = ehci_hub_power_off,
+};
+
+static inline int omap_ehci_hub_port(struct device *dev)
+{
+ /* we expect dev->parent points to ehcd controller */
+ if (dev->parent && !strcmp(dev_name(dev->parent), "ehci-omap.0"))
+ return 1;
+ return 0;
+}
+
+static inline int dev_pc_match(struct device *dev)
+{
+ struct device *anc;
+ int ret = 0;
+
+ if (likely(strcmp(dev_name(dev), "port1")))
+ goto exit;
+
+ if (dev->parent && (anc = dev->parent->parent)) {
+ if (omap_ehci_hub_port(anc)) {
+ ret = 1;
+ goto exit;
+ }
+
+ /* is it port of lan95xx hub? */
+ if ((anc = anc->parent) && omap_ehci_hub_port(anc)) {
+ ret = 2;
+ goto exit;
+ }
+ }
+exit:
+ return ret;
+}
+
+/*
+ * Notifications of device registration
+ */
+static int device_notify(struct notifier_block *nb, unsigned long action,
void *data)
+{
+ struct device *dev = data;
+ int ret;
+
+ switch (action) {
+ case DEV_NOTIFY_ADD_DEVICE:
+ ret = dev_pc_match(dev);
+ if (likely(!ret))
+ goto exit;
+ if (ret == 1)
+ dev_pc_bind(&pc, dev, &root_hub_port_data,
sizeof(root_hub_port_data));
+ else
+ dev_pc_bind(&pc, dev, &smsc_hub_port_data,
sizeof(smsc_hub_port_data));
+ break;
+
+ case DEV_NOTIFY_DEL_DEVICE:
+ break;
+ }
+exit:
+ return 0;
+}
+
+static struct notifier_block usb_port_nb = {
+ .notifier_call = device_notify,
+};
+
Some thoughts on trying to make this functionality specific to power only
and ehci hub port only:
- Quite a few boards have smsc95xx... they're all going to carry these
additions in the board file? Surely you'll have to generalize the pieces
All things are board dependent because we are discussing peripheral
device(not builtin SoC devices), so it is proper to put it in the board file.
If some boards want to share it, we can put it in a single .c file and
let board file include it.
Where would the .c file go... SMSC is not platform, or even arch
specific chip (eg, iMX or MIPS or even x86 boards can have it), so not
arch/arm/mach-xxxx or arch/arm/plat-xxx or arch/arm. I guess it would
go in drivers/usb or drivers/net.
Push in ARM-Land is towards single kernels which support many platforms,
a good case in point is omap2plus_defconfg which wants to allow to
support all OMAP2/3/4/5 platforms in one kernel. If you "include" that
C file over and over in board files, it's not very nice for that. They
anyway want to eliminate board files for the single kernel binary
reason, and just have one load of config come in by dtb.
So it guides you towards having static helper code once in drivers/ for
the scenarios you support... if that's where you end up smsc is less
good a target for a helper than to have helpers for classes of object
like regulator and clk, that you can combine and reuse on all sorts of
target devices, which is device_asset approach.
It also guides you to having the special platform sauce be something
that can go into the dtb: per-board code can't. That's why device_asset
stuff only places asset structs in the board file and is removing code
from there.
that perform device_path business out of the omap4panda board file at least.
At that point the path matching code becomes generic end-of-the-device-path
matching code.
Looks Alan has mentioned, there might be no generic way, and any device's
name change in the path may make the way fragile.
What you have provided is no less fragile if you allow "port1" and the
ehci-omap.0 to be set from the outside.
Unless someone NAKs it for sure already (if you're already sure you're
going to, please do so to avoid wasting time), I'll issue a try#2 of my
code later which demonstrates what I mean. At least I guess it's useful
for comparative purposes.
- How could these literals like "port1" etc be nicely provided by Device
Tree? In ARM-land there's pressure to eventually eliminate board files
completely and pass in everything from dtb. device_asset can neatly grow DT
bindings in a generic way, since the footprint in the board file is some
IMO, it isn't necessary to expose these assets to device or users, from the
view of device or user, which only cares two actions(poweron and poweroff)
about the discussed problem. Also it should be better to put these assets
into device resource list, instead of introducing them in 'struct device'.
From the point of view of allowing it to be reused on different boards
/ platforms / arches, you are going to have to do something better than
have literals in the code.
regulators that already have dt bindings and some device_asset structs.
Similarly there's pressure for magic code to service a board (rather than
SoC) to go elsewhere than the board file.
Looks you associate these assets with ehci-omap device, which mightn't be
enough, because we need to control port's power for supporting port
power off mechanism. Do you have generic way to associate these assets
with usb port device and let port use it generally?
Yes, you need a parent device pointer (ehci host controller in this
case) and the path rhs, but only stuff that is defined by usb stack
code. Needing a parent pointer is OK because this stuff only has
meaning for hardwired assets on the platform, so the parent device will
always be known as a platform_device at boot time anyway.
The code I'll provide will work the same in sdio or other bus case, just
use mmc host controller pointer and the sdio device name the same way.
- Shouldn't this take care of enabling and disabling the ULPI PHY clock on
Panda too? There's no purpose leaving it running if the one thing the ULPI
PHY is connected to is depowered, and when you do power it, on Panda you
will reset the ULPI PHY at the same time anyway (smsc reset and ULPI PHY
reset are connected together on Panda). Then you can eliminate
omap4_ehci_init() in the board file.
OK, we can include the ULPI PHY clock things easily in ->power_on() and
->power_off() of 'power controller'
Yes if the ARM people will accept establishing more code in board files
that doesn't have a DT story.
-Andy
--
Andy Green | TI Landing Team Leader
Linaro.org │ Open source software for ARM SoCs | Follow Linaro
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