linux/drivers/soundwire/bus.h
Pierre-Louis Bossart 2140b66b5d soundwire: bus: fix race condition with probe_complete signaling
The driver probe takes care of basic initialization and is invoked
when a Slave becomes attached, after a match between the Slave DevID
registers and ACPI/DT entries.

The update_status callback is invoked when a Slave state changes,
e.g. when it is assigned a non-zero Device Number and it reports with
an ATTACHED/ALERT state.

The state change detection is usually hardware-based and based on the
SoundWire frame rate (e.g. double-digit microseconds) while the probe
is a pure software operation, which may involve a kernel module
load. In corner cases, it's possible that the state changes before the
probe completes.

This patch suggests the use of wait_for_completion to avoid races on
startup, so that the update_status callback does not rely on invalid
pointers/data structures.

Signed-off-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200115000844.14695-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
2020-02-25 15:57:01 +05:30

169 lines
4.5 KiB
C

/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
/* Copyright(c) 2015-17 Intel Corporation. */
#ifndef __SDW_BUS_H
#define __SDW_BUS_H
#define DEFAULT_BANK_SWITCH_TIMEOUT 3000
#define DEFAULT_PROBE_TIMEOUT 2000
#if IS_ENABLED(CONFIG_ACPI)
int sdw_acpi_find_slaves(struct sdw_bus *bus);
#else
static inline int sdw_acpi_find_slaves(struct sdw_bus *bus)
{
return -ENOTSUPP;
}
#endif
int sdw_of_find_slaves(struct sdw_bus *bus);
void sdw_extract_slave_id(struct sdw_bus *bus,
u64 addr, struct sdw_slave_id *id);
#ifdef CONFIG_DEBUG_FS
void sdw_bus_debugfs_init(struct sdw_bus *bus);
void sdw_bus_debugfs_exit(struct sdw_bus *bus);
void sdw_slave_debugfs_init(struct sdw_slave *slave);
void sdw_slave_debugfs_exit(struct sdw_slave *slave);
void sdw_debugfs_init(void);
void sdw_debugfs_exit(void);
#else
static inline void sdw_bus_debugfs_init(struct sdw_bus *bus) {}
static inline void sdw_bus_debugfs_exit(struct sdw_bus *bus) {}
static inline void sdw_slave_debugfs_init(struct sdw_slave *slave) {}
static inline void sdw_slave_debugfs_exit(struct sdw_slave *slave) {}
static inline void sdw_debugfs_init(void) {}
static inline void sdw_debugfs_exit(void) {}
#endif
enum {
SDW_MSG_FLAG_READ = 0,
SDW_MSG_FLAG_WRITE,
};
/**
* struct sdw_msg - Message structure
* @addr: Register address accessed in the Slave
* @len: number of messages
* @dev_num: Slave device number
* @addr_page1: SCP address page 1 Slave register
* @addr_page2: SCP address page 2 Slave register
* @flags: transfer flags, indicate if xfer is read or write
* @buf: message data buffer
* @ssp_sync: Send message at SSP (Stream Synchronization Point)
* @page: address requires paging
*/
struct sdw_msg {
u16 addr;
u16 len;
u8 dev_num;
u8 addr_page1;
u8 addr_page2;
u8 flags;
u8 *buf;
bool ssp_sync;
bool page;
};
#define SDW_DOUBLE_RATE_FACTOR 2
extern int sdw_rows[SDW_FRAME_ROWS];
extern int sdw_cols[SDW_FRAME_COLS];
int sdw_find_row_index(int row);
int sdw_find_col_index(int col);
/**
* sdw_port_runtime: Runtime port parameters for Master or Slave
*
* @num: Port number. For audio streams, valid port number ranges from
* [1,14]
* @ch_mask: Channel mask
* @transport_params: Transport parameters
* @port_params: Port parameters
* @port_node: List node for Master or Slave port_list
*
* SoundWire spec has no mention of ports for Master interface but the
* concept is logically extended.
*/
struct sdw_port_runtime {
int num;
int ch_mask;
struct sdw_transport_params transport_params;
struct sdw_port_params port_params;
struct list_head port_node;
};
/**
* sdw_slave_runtime: Runtime Stream parameters for Slave
*
* @slave: Slave handle
* @direction: Data direction for Slave
* @ch_count: Number of channels handled by the Slave for
* this stream
* @m_rt_node: sdw_master_runtime list node
* @port_list: List of Slave Ports configured for this stream
*/
struct sdw_slave_runtime {
struct sdw_slave *slave;
enum sdw_data_direction direction;
unsigned int ch_count;
struct list_head m_rt_node;
struct list_head port_list;
};
/**
* sdw_master_runtime: Runtime stream parameters for Master
*
* @bus: Bus handle
* @stream: Stream runtime handle
* @direction: Data direction for Master
* @ch_count: Number of channels handled by the Master for
* this stream, can be zero.
* @slave_rt_list: Slave runtime list
* @port_list: List of Master Ports configured for this stream, can be zero.
* @stream_node: sdw_stream_runtime master_list node
* @bus_node: sdw_bus m_rt_list node
*/
struct sdw_master_runtime {
struct sdw_bus *bus;
struct sdw_stream_runtime *stream;
enum sdw_data_direction direction;
unsigned int ch_count;
struct list_head slave_rt_list;
struct list_head port_list;
struct list_head stream_node;
struct list_head bus_node;
};
struct sdw_dpn_prop *sdw_get_slave_dpn_prop(struct sdw_slave *slave,
enum sdw_data_direction direction,
unsigned int port_num);
int sdw_configure_dpn_intr(struct sdw_slave *slave, int port,
bool enable, int mask);
int sdw_transfer(struct sdw_bus *bus, struct sdw_msg *msg);
int sdw_transfer_defer(struct sdw_bus *bus, struct sdw_msg *msg,
struct sdw_defer *defer);
#define SDW_READ_INTR_CLEAR_RETRY 10
int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
u32 addr, size_t count, u16 dev_num, u8 flags, u8 *buf);
/* Read-Modify-Write Slave register */
static inline int
sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
{
int tmp;
tmp = sdw_read(slave, addr);
if (tmp < 0)
return tmp;
tmp = (tmp & ~mask) | val;
return sdw_write(slave, addr, tmp);
}
#endif /* __SDW_BUS_H */