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staging: fsl-mc:Added support for atomic portals

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Refactored mc_send_command() to support two flavors of polling:
- preemptible (for non-atomic portals), which was already supported.
  It calls usleep_range() between polling iterations.
- non-preemptible (for atomic portals), which is needed when
  mc_send_command() is called with interrupts disabled.
  It calls udelay() between polling iterations.

Signed-off-by: J. German Rivera <German.Rivera@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
J. German Rivera 2015-10-17 15:33:14 -05:00 committed by Greg Kroah-Hartman
parent 140305e77a
commit 3f95ad2185
2 changed files with 55 additions and 3 deletions
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53
drivers/staging/fsl-mc/bus/mc-sys.c
View File

@ -338,6 +338,47 @@ static int mc_polling_wait_preemptible(struct fsl_mc_io *mc_io,
return 0;
}
/**
* Waits for the completion of an MC command doing atomic polling.
* udelay() is called between polling iterations.
*
* @mc_io: MC I/O object to be used
* @cmd: command buffer to receive MC response
* @mc_status: MC command completion status
*/
static int mc_polling_wait_atomic(struct fsl_mc_io *mc_io,
struct mc_command *cmd,
enum mc_cmd_status *mc_status)
{
enum mc_cmd_status status;
unsigned long timeout_usecs = MC_CMD_COMPLETION_TIMEOUT_MS * 1000;
BUILD_BUG_ON((MC_CMD_COMPLETION_TIMEOUT_MS * 1000) %
MC_CMD_COMPLETION_POLLING_MAX_SLEEP_USECS != 0);
for (;;) {
status = mc_read_response(mc_io->portal_virt_addr, cmd);
if (status != MC_CMD_STATUS_READY)
break;
udelay(MC_CMD_COMPLETION_POLLING_MAX_SLEEP_USECS);
timeout_usecs -= MC_CMD_COMPLETION_POLLING_MAX_SLEEP_USECS;
if (timeout_usecs == 0) {
pr_debug("MC command timed out (portal: %#llx, obj handle: %#x, command: %#x)\n",
mc_io->portal_phys_addr,
(unsigned int)
MC_CMD_HDR_READ_TOKEN(cmd->header),
(unsigned int)
MC_CMD_HDR_READ_CMDID(cmd->header));
return -ETIMEDOUT;
}
}
*mc_status = status;
return 0;
}
/**
* Sends a command to the MC device using the given MC I/O object
*
@ -345,14 +386,16 @@ static int mc_polling_wait_preemptible(struct fsl_mc_io *mc_io,
* @cmd: command to be sent
*
* Returns '0' on Success; Error code otherwise.
*
* NOTE: This function cannot be invoked from from atomic contexts.
*/
int mc_send_command(struct fsl_mc_io *mc_io, struct mc_command *cmd)
{
int error;
enum mc_cmd_status status;
if (WARN_ON(in_irq() &&
!(mc_io->flags & FSL_MC_IO_ATOMIC_CONTEXT_PORTAL)))
return -EINVAL;
/*
* Send command to the MC hardware:
*/
@ -361,7 +404,11 @@ int mc_send_command(struct fsl_mc_io *mc_io, struct mc_command *cmd)
/*
* Wait for response from the MC hardware:
*/
error = mc_polling_wait_preemptible(mc_io, cmd, &status);
if (!(mc_io->flags & FSL_MC_IO_ATOMIC_CONTEXT_PORTAL))
error = mc_polling_wait_preemptible(mc_io, cmd, &status);
else
error = mc_polling_wait_atomic(mc_io, cmd, &status);
if (error < 0)
return error;

5
drivers/staging/fsl-mc/include/mc-sys.h
View File

@ -40,6 +40,11 @@
#include <linux/io.h>
#include <linux/dma-mapping.h>
/**
* Bit masks for a MC I/O object (struct fsl_mc_io) flags
*/
#define FSL_MC_IO_ATOMIC_CONTEXT_PORTAL 0x0001
struct fsl_mc_resource;
struct mc_command;