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Date: Mon, 4 Jun 2018 17:06:50 -0700
From: Gwendal Grignou <gwendal@...omium.org>
To: Enrico Granata <egranata@...gle.com>
Cc: Linux Kernel <linux-kernel@...r.kernel.org>, egranata@...omium.org,
Benson Leung <bleung@...omium.org>,
Olof Johansson <olof@...om.net>,
Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH] Cleanup dependency chain for cros_ec modules
On Mon, Jun 4, 2018 at 1:22 PM Enrico Granata <egranata@...gle.com> wrote:
>
> From: Enrico Granata <egranata@...omium.org>
>
> If one builds the Chrome EC support as modules, there is no explicit
> dependency chain amongst the several modules (LPC, CHARDEV, CORE, ...)
>
> This makes it possible - for instance - to rmmod cros_ec_core, even though
> cros_ec_dev actively uses it for data transport to the EC chip.
>
> This commit makes two changes in an attempt to address this:
> a) moves cros_ec_proto.c as part of the CORE module; this removes the
> possibility of unloading cros_ec_core while cros_ec_dev is using it;
> b) enables cros_ec_core to explicitly register a runtime dependency on
> the kernel module that is using its cmd and pkt transfer functions
>
> Signed-off-by: Enrico Granata <egranata@...omium.org>
> ---
>
> drivers/mfd/Kconfig | 1 -
> drivers/mfd/Makefile | 2 +-
> drivers/mfd/cros_ec.c | 17 ++++++++++++++++-
> .../{platform/chrome => mfd}/cros_ec_proto.c | 0
> drivers/platform/chrome/Kconfig | 5 -----
> drivers/platform/chrome/Makefile | 1 -
> drivers/platform/chrome/cros_ec_lpc.c | 1 +
> include/linux/mfd/cros_ec.h | 2 ++
> 8 files changed, 20 insertions(+), 9 deletions(-)
> rename drivers/{platform/chrome => mfd}/cros_ec_proto.c (100%)
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index b860eb5aa194..a8daa2072ae6 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -194,7 +194,6 @@ config MFD_CROS_EC
> tristate "ChromeOS Embedded Controller"
> select MFD_CORE
> select CHROME_PLATFORMS
> - select CROS_EC_PROTO
> depends on X86 || ARM || ARM64 || COMPILE_TEST
> help
> If you say Y here you get support for the ChromeOS Embedded
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index d9d2cf0d32ef..20537bd27695 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -12,7 +12,7 @@ obj-$(CONFIG_MFD_SM501) += sm501.o
> obj-$(CONFIG_MFD_ASIC3) += asic3.o tmio_core.o
> obj-$(CONFIG_MFD_BCM590XX) += bcm590xx.o
> obj-$(CONFIG_MFD_BD9571MWV) += bd9571mwv.o
> -cros_ec_core-objs := cros_ec.o
> +cros_ec_core-objs := cros_ec.o cros_ec_proto.o
We try to get cros_ec_proto out of mfd directory, it is weird to
compile something from drivers/platform/chrome/ in drivers/mfd.
> cros_ec_core-$(CONFIG_ACPI) += cros_ec_acpi_gpe.o
> obj-$(CONFIG_MFD_CROS_EC) += cros_ec_core.o
> obj-$(CONFIG_MFD_CROS_EC_I2C) += cros_ec_i2c.o
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index d61024141e2b..109e9cb1e289 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -168,9 +168,21 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
> */
> err = cros_ec_sleep_event(ec_dev, 0);
> if (err < 0)
> - dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
> + dev_dbg(dev, "Error %d clearing sleep event to ec",
> err);
Concatenate both line.
>
> + if (ec_dev->xfer_fcn_owner != NULL) {
> + err = try_module_get(ec_dev->xfer_fcn_owner);
> + if (err < 0) {
> + dev_err(dev, "Error %d acquiring transfer module", err);
> + return err;
> + }
> + dev_info(dev, "Transfer module %p get successfully",
> + ec_dev->xfer_fcn_owner);
> + } else {
> + dev_warn(dev, "No transfer module registered");
> + }
> +
> dev_info(dev, "Chrome EC device registered\n");
>
> cros_ec_acpi_install_gpe_handler(dev);
> @@ -193,6 +205,9 @@ int cros_ec_remove(struct cros_ec_device *ec_dev)
> if (ec_dev->irq)
> free_irq(ec_dev->irq, ec_dev);
>
> + if (ec_dev->xfer_fcn_owner != NULL)
> + module_put(ec_dev->xfer_fcn_owner);
> +
> return 0;
> }
> EXPORT_SYMBOL(cros_ec_remove);
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/mfd/cros_ec_proto.c
> similarity index 100%
> rename from drivers/platform/chrome/cros_ec_proto.c
> rename to drivers/mfd/cros_ec_proto.c
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index e728a96cabfd..a050c9e8b506 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -65,11 +65,6 @@ config CROS_EC_LPC_MEC
> If you have a ChromeOS Embedded Controller Microchip EC variant
> choose Y here.
>
> -config CROS_EC_PROTO
> - bool
> - help
> - ChromeOS EC communication protocol helpers.
> -
> config CROS_KBD_LED_BACKLIGHT
> tristate "Backlight LED support for Chrome OS keyboards"
> depends on LEDS_CLASS && ACPI
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index ff3b369911f0..0b5e26ca9c96 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -8,5 +8,4 @@ obj-$(CONFIG_CROS_EC_CTL) += cros_ec_ctl.o
> cros_ec_lpcs-objs := cros_ec_lpc.o cros_ec_lpc_reg.o
> cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC) += cros_ec_lpc_mec.o
> obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpcs.o
> -obj-$(CONFIG_CROS_EC_PROTO) += cros_ec_proto.o
> obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT) += cros_kbd_led_backlight.o
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
> index 3682e1539251..8f02b188bd3f 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -282,6 +282,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
> ec_dev->phys_name = dev_name(dev);
> ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
> ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
> + ec_dev->xfer_fcn_owner = THIS_MODULE;
You need to modify other transport modules as well:
cros_ec_i2c.c, cros_ec_spi.c.
> ec_dev->cmd_readmem = cros_ec_lpc_readmem;
> ec_dev->din_size = sizeof(struct ec_host_response) +
> sizeof(struct ec_response_get_protocol_info);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 2d4e23c9ea0a..5239107e5091 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -18,6 +18,7 @@
>
> #include <linux/cdev.h>
> #include <linux/device.h>
> +#include <linux/module.h>
> #include <linux/notifier.h>
> #include <linux/mfd/cros_ec_commands.h>
> #include <linux/mutex.h>
> @@ -139,6 +140,7 @@ struct cros_ec_device {
> int dout_size;
> bool wake_enabled;
> bool suspended;
> + struct module *xfer_fcn_owner;
Another solution would be to make cros_ec a real module. lpc depends
on cros_ec_register, so lsmod will not unload cros_ec [core functions]
if cros_ec_lpc is still loaded.
> int (*cmd_xfer)(struct cros_ec_device *ec,
> struct cros_ec_command *msg);
> int (*pkt_xfer)(struct cros_ec_device *ec,
> --
> 2.17.1.1185.g55be947832-goog
>
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