Re: [PATCH v4 14/38] platform/x86: intel_scu_ipc: Introduce new SCU IPC API

Mika Westerberg
2020-01-22T14:40:58Z

On Wed, Jan 22, 2020 at 02:43:59PM +0100, Greg Kroah-Hartman wrote:
> On Tue, Jan 21, 2020 at 07:00:50PM +0300, Mika Westerberg wrote:
> > The current SCU IPC API has been operating on a single instance and
> > there has been no way to pin the providing module in place when the SCU
> > IPC is in use.
> >
> > This implements a new API that takes the SCU IPC instance as first
> > parameter (NULL means the single instance is being used). The SCU IPC
> > instance can be retrieved by calling new function
> > intel_scu_ipc_dev_get() that take care of pinning the providing module
> > in place as long as intel_scu_ipc_dev_put() is not called.
> >
> > The old API is left there to support existing users which cannot be
> > converted easily but it is put to a separate header that is subject to
> > be removed eventually. Subsequent patches will convert most of the users
> > to the new API.
> >
> > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > ---
> > arch/x86/include/asm/intel_scu_ipc.h | 74 +++----
> > arch/x86/include/asm/intel_scu_ipc_legacy.h | 76 +++++++
> > drivers/platform/x86/intel_scu_ipc.c | 219 ++++++++++++++++----
> > drivers/platform/x86/intel_scu_pcidrv.c | 7 +-
> > 4 files changed, 287 insertions(+), 89 deletions(-)
> > create mode 100644 arch/x86/include/asm/intel_scu_ipc_legacy.h
> >
> > diff --git a/arch/x86/include/asm/intel_scu_ipc.h b/arch/x86/include/asm/intel_scu_ipc.h
> > index 252ea0046f16..ce2ad516f0f9 100644
> > --- a/arch/x86/include/asm/intel_scu_ipc.h
> > +++ b/arch/x86/include/asm/intel_scu_ipc.h
> > @@ -1,9 +1,8 @@
> > /* SPDX-License-Identifier: GPL-2.0 */
> > #ifndef _ASM_X86_INTEL_SCU_IPC_H_
> > -#define _ASM_X86_INTEL_SCU_IPC_H_
> > +#define _ASM_X86_INTEL_SCU_IPC_H_
>
> gratuitous change :(

Oops.

> > #include <linux/ioport.h>
> > -#include <linux/notifier.h>
> >
> > #define IPCMSG_INDIRECT_READ 0x02
> > #define IPCMSG_INDIRECT_WRITE 0x05
> > @@ -21,6 +20,7 @@
> > #define IPC_CMD_VRTC_SETALARM 2 /* Set alarm */
> >
> > struct device;
> > +struct intel_scu_ipc_dev;
> >
> > /**
> > * struct intel_scu_ipc_pdata - Platform data for SCU IPC
> > @@ -32,47 +32,39 @@ struct intel_scu_ipc_pdata {
> > int irq;
> > };
> >
> > -int intel_scu_ipc_register(struct device *dev,
> > - const struct intel_scu_ipc_pdata *pdata);
> > -
> > -/* Read single register */
> > -int intel_scu_ipc_ioread8(u16 addr, u8 *data);
> > -
> > -/* Read a vector */
> > -int intel_scu_ipc_readv(u16 *addr, u8 *data, int len);
> > -
> > -/* Write single register */
> > -int intel_scu_ipc_iowrite8(u16 addr, u8 data);
> > -
> > -/* Write a vector */
> > -int intel_scu_ipc_writev(u16 *addr, u8 *data, int len);
> > -
> > -/* Update single register based on the mask */
> > -int intel_scu_ipc_update_register(u16 addr, u8 data, u8 mask);
> > -
> > -/* Issue commands to the SCU with or without data */
> > -int intel_scu_ipc_simple_command(int cmd, int sub);
> > -int intel_scu_ipc_command(int cmd, int sub, u32 *in, int inlen,
> > - u32 *out, int outlen);
> > -
> > -extern struct blocking_notifier_head intel_scu_notifier;
> > -
> > -static inline void intel_scu_notifier_add(struct notifier_block *nb)
> > -{
> > - blocking_notifier_chain_register(&intel_scu_notifier, nb);
> > -}
> > -
> > -static inline void intel_scu_notifier_remove(struct notifier_block *nb)
> > -{
> > - blocking_notifier_chain_unregister(&intel_scu_notifier, nb);
> > -}
> > -
> > -static inline int intel_scu_notifier_post(unsigned long v, void *p)
> > +struct intel_scu_ipc_dev *
> > +intel_scu_ipc_register(struct device *dev, const struct intel_scu_ipc_pdata *pdata);
> > +
> > +struct intel_scu_ipc_dev *intel_scu_ipc_dev_get(void);
> > +void intel_scu_ipc_dev_put(struct intel_scu_ipc_dev *scu);
> > +struct intel_scu_ipc_dev *devm_intel_scu_ipc_dev_get(struct device *dev);
> > +
> > +int intel_scu_ipc_dev_ioread8(struct intel_scu_ipc_dev *scu, u16 addr,
> > + u8 *data);
> > +int intel_scu_ipc_dev_iowrite8(struct intel_scu_ipc_dev *scu, u16 addr,
> > + u8 data);
> > +int intel_scu_ipc_dev_readv(struct intel_scu_ipc_dev *scu, u16 *addr,
> > + u8 *data, size_t len);
> > +int intel_scu_ipc_dev_writev(struct intel_scu_ipc_dev *scu, u16 *addr,
> > + u8 *data, size_t len);
> > +
> > +int intel_scu_ipc_dev_update(struct intel_scu_ipc_dev *scu, u16 addr,
> > + u8 data, u8 mask);
> > +
> > +int intel_scu_ipc_dev_simple_command(struct intel_scu_ipc_dev *scu, int cmd,
> > + int sub);
> > +int intel_scu_ipc_dev_command_with_size(struct intel_scu_ipc_dev *scu, int cmd,
> > + int sub, const void *in, size_t inlen,
> > + size_t size, void *out, size_t outlen);
> > +
> > +static inline int intel_scu_ipc_dev_command(struct intel_scu_ipc_dev *scu, int cmd,
> > + int sub, const void *in, size_t inlen,
> > + void *out, size_t outlen)
> > {
> > - return blocking_notifier_call_chain(&intel_scu_notifier, v, p);
> > + return intel_scu_ipc_dev_command_with_size(scu, cmd, sub, in, inlen,
> > + inlen, out, outlen);
> > }
> >
> > -#define SCU_AVAILABLE 1
> > -#define SCU_DOWN 2
> > +#include <asm/intel_scu_ipc_legacy.h>
> >
> > #endif
> > diff --git a/arch/x86/include/asm/intel_scu_ipc_legacy.h b/arch/x86/include/asm/intel_scu_ipc_legacy.h
> > new file mode 100644
> > index 000000000000..3399ea8eea48
> > --- /dev/null
> > +++ b/arch/x86/include/asm/intel_scu_ipc_legacy.h
> > @@ -0,0 +1,76 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _ASM_X86_INTEL_SCU_IPC_LEGACY_H_
> > +#define _ASM_X86_INTEL_SCU_IPC_LEGACY_H_
> > +
> > +#include <linux/notifier.h>
> > +
> > +/* Don't call these in new code - they will be removed eventually */
> > +
> > +/* Read single register */
> > +static inline int intel_scu_ipc_ioread8(u16 addr, u8 *data)
> > +{
> > + return intel_scu_ipc_dev_ioread8(NULL, addr, data);
> > +}
> > +
> > +/* Read a vector */
> > +static inline int intel_scu_ipc_readv(u16 *addr, u8 *data, int len)
> > +{
> > + return intel_scu_ipc_dev_readv(NULL, addr, data, len);
> > +}
> > +
> > +/* Write single register */
> > +static inline int intel_scu_ipc_iowrite8(u16 addr, u8 data)
> > +{
> > + return intel_scu_ipc_dev_iowrite8(NULL, addr, data);
> > +}
> > +
> > +/* Write a vector */
> > +static inline int intel_scu_ipc_writev(u16 *addr, u8 *data, int len)
> > +{
> > + return intel_scu_ipc_dev_writev(NULL, addr, data, len);
> > +}
> > +
> > +/* Update single register based on the mask */
> > +static inline int intel_scu_ipc_update_register(u16 addr, u8 data, u8 mask)
> > +{
> > + return intel_scu_ipc_dev_update(NULL, addr, data, mask);
> > +}
> > +
> > +/* Issue commands to the SCU with or without data */
> > +static inline int intel_scu_ipc_simple_command(int cmd, int sub)
> > +{
> > + return intel_scu_ipc_dev_simple_command(NULL, cmd, sub);
> > +}
> > +
> > +static inline int intel_scu_ipc_command(int cmd, int sub, u32 *in, int inlen,
> > + u32 *out, int outlen)
> > +{
> > + /* New API takes both inlen and outlen as bytes so convert here */
> > + size_t inbytes = inlen * sizeof(u32);
> > + size_t outbytes = outlen * sizeof(u32);
> > +
> > + return intel_scu_ipc_dev_command_with_size(NULL, cmd, sub, in, inbytes,
> > + inlen, out, outbytes);
> > +}
> > +
> > +extern struct blocking_notifier_head intel_scu_notifier;
> > +
> > +static inline void intel_scu_notifier_add(struct notifier_block *nb)
> > +{
> > + blocking_notifier_chain_register(&intel_scu_notifier, nb);
> > +}
> > +
> > +static inline void intel_scu_notifier_remove(struct notifier_block *nb)
> > +{
> > + blocking_notifier_chain_unregister(&intel_scu_notifier, nb);
> > +}
> > +
> > +static inline int intel_scu_notifier_post(unsigned long v, void *p)
> > +{
> > + return blocking_notifier_call_chain(&intel_scu_notifier, v, p);
> > +}
> > +
> > +#define SCU_AVAILABLE 1
> > +#define SCU_DOWN 2
> > +
> > +#endif
> > diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c
> > index 518b044d8ecb..391b65a4789e 100644
> > --- a/drivers/platform/x86/intel_scu_ipc.c
> > +++ b/drivers/platform/x86/intel_scu_ipc.c
> > @@ -19,6 +19,7 @@
> > #include <linux/init.h>
> > #include <linux/interrupt.h>
> > #include <linux/io.h>
> > +#include <linux/module.h>
> >
> > #include <asm/intel_scu_ipc.h>
> >
> > @@ -78,6 +79,99 @@ static struct intel_scu_ipc_dev ipcdev; /* Only one for now */
> >
> > static DEFINE_MUTEX(ipclock); /* lock used to prevent multiple call to SCU */
> >
> > +/**
> > + * intel_scu_ipc_dev_get() - Get SCU IPC instance
> > + *
> > + * The recommended new API takes SCU IPC instance as parameter and this
> > + * function can be called by driver to get the instance. This also makes
> > + * sure the driver providing the IPC functionality cannot be unloaded
> > + * while the caller has the intance.
> > + *
> > + * Call intel_scu_ipc_dev_put() to release the instance.
> > + *
> > + * Returns %NULL if SCU IPC is not currently available.
> > + */
> > +struct intel_scu_ipc_dev *intel_scu_ipc_dev_get(void)
> > +{
> > + struct intel_scu_ipc_dev *scu = &ipcdev;
> > +
> > + mutex_lock(&ipclock);
> > + if (!scu->dev)
> > + goto err_unlock;
> > + if (!try_module_get(scu->dev->driver->owner))
> > + goto err_unlock;
> > + mutex_unlock(&ipclock);
> > + return scu;
>
> NO REFERENCE COUNT INCREMENT???

You mean increment the scu->dev reference count? I kind of thought that
the try_module_get() should make sure the thing stays there as long as
the caller has not called _put() but now when I think about it bit more
we would need to do device_get() here as well.

Sorry about this.

> You owe me 5 recitations of the "Data Structures" of
> Documentation/process/coding-style.rst
>
> And some whisky to get me through the next round of code reviews of this
> mess...

Sure :)