[PATCH v3] cros_ec: cleanup dependency chain for cros_ec modules

From: Enrico Granata
Date: Mon Jun 04 2018 - 20:44:15 EST

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In reply to: Enrico Granata: "[PATCH v2] cros_ec: cleanup dependency chain for cros_ec modules"
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From: Enrico Granata <egranata@xxxxxxxxxxxx>

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

Series-to: LKML <linux-kernel@xxxxxxxxxxxxxxx>
Series-cc: gwendal@xxxxxxxxxx
Signed-off-by: Enrico Granata <egranata@xxxxxxxxxxxx>
---
drivers/mfd/Kconfig | 1 -
drivers/mfd/Makefile | 2 +-
drivers/mfd/cros_ec.c | 18 ++++++++++++++++--
drivers/mfd/cros_ec_i2c.c | 1 +
drivers/{platform/chrome => mfd}/cros_ec_proto.c | 0
drivers/mfd/cros_ec_spi.c | 1 +
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 ++
10 files changed, 22 insertions(+), 10 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
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..9660dc0fc079 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -168,8 +168,19 @@ 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",
- err);
+ dev_dbg(dev, "Error %d clearing sleep event to ec", err);
+
+ 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");

@@ -193,6 +204,9 @@ 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/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
index 9f70de1e4c70..72b0473eb868 100644
--- a/drivers/mfd/cros_ec_i2c.c
+++ b/drivers/mfd/cros_ec_i2c.c
@@ -302,6 +302,7 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
ec_dev->irq = client->irq;
ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
+ ec_dev->xfer_fcn_owner = THIS_MODULE;
ec_dev->phys_name = client->adapter->name;
ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
sizeof(struct ec_response_get_protocol_info);
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/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index 2060d1483043..ce2849790b95 100644
--- a/drivers/mfd/cros_ec_spi.c
+++ b/drivers/mfd/cros_ec_spi.c
@@ -666,6 +666,7 @@ static int cros_ec_spi_probe(struct spi_device *spi)
ec_dev->irq = spi->irq;
ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
ec_dev->pkt_xfer = cros_ec_pkt_xfer_spi;
+ ec_dev->xfer_fcn_owner = THIS_MODULE;
ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
sizeof(struct ec_host_response) +
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;
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;
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

Next message: Mike Snitzer: "Re: [PATCH v2 5/7] dm: remove DM_TYPE_DAX_BIO_BASED dm_queue_mode"
Previous message: Ming Lei: "Re: INFO: task hung in blk_queue_enter"
In reply to: Enrico Granata: "[PATCH v2] cros_ec: cleanup dependency chain for cros_ec modules"
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