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    SubjectRe: [PATCH 6/7] staging: fsl-mc: rewrite mc command send/receive to work on 32-bits
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    On 17/07/17 14:26, laurentiu.tudor@nxp.com wrote:
    > From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
    >
    > Split the 64-bit accesses in 32-bit accesses because there's no real
    > constrain in MC to do only atomic 64-bit. There's only one place
    > where ordering is important: when writing the MC command header the
    > first 32-bit part of the header must be written last.
    > We do this switch in order to allow compiling the driver on 32-bit.

    #include <linux/io-64-nonatomic-hi-lo.h>

    Then you can just use writeq()/writeq_relaxed()/readq_relaxed() on
    32-bit platforms as well.

    Robin.

    > Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
    > ---
    > drivers/staging/fsl-mc/bus/mc-sys.c | 31 ++++++++++++-------------------
    > 1 file changed, 12 insertions(+), 19 deletions(-)
    >
    > diff --git a/drivers/staging/fsl-mc/bus/mc-sys.c b/drivers/staging/fsl-mc/bus/mc-sys.c
    > index 195d9f3..dd2828e 100644
    > --- a/drivers/staging/fsl-mc/bus/mc-sys.c
    > +++ b/drivers/staging/fsl-mc/bus/mc-sys.c
    > @@ -124,14 +124,15 @@ static inline void mc_write_command(struct mc_command __iomem *portal,
    > {
    > int i;
    >
    > - /* copy command parameters into the portal */
    > - for (i = 0; i < MC_CMD_NUM_OF_PARAMS; i++)
    > - __raw_writeq(cmd->params[i], &portal->params[i]);
    > - /* ensure command params are committed before submitting it */
    > - wmb();
    > -
    > - /* submit the command by writing the header */
    > - __raw_writeq(cmd->header, &portal->header);
    > + /*
    > + * copy command parameters into the portal. Final write
    > + * triggers the submission of the command.
    > + */
    > + for (i = sizeof(struct mc_command) / sizeof(u32) - 1; i >= 0; i--) {
    > + __raw_writel(((u32 *)cmd)[i], &((u32 *)portal)[i]);
    > + /* ensure command params are committed before submitting it */
    > + wmb();
    > + }
    > }
    >
    > /**
    > @@ -148,19 +149,11 @@ static inline enum mc_cmd_status mc_read_response(struct mc_command __iomem *
    > struct mc_command *resp)
    > {
    > int i;
    > - enum mc_cmd_status status;
    > -
    > - /* Copy command response header from MC portal: */
    > - resp->header = __raw_readq(&portal->header);
    > - status = mc_cmd_hdr_read_status(resp);
    > - if (status != MC_CMD_STATUS_OK)
    > - return status;
    >
    > - /* Copy command response data from MC portal: */
    > - for (i = 0; i < MC_CMD_NUM_OF_PARAMS; i++)
    > - resp->params[i] = __raw_readq(&portal->params[i]);
    > + for (i = 0; i < sizeof(struct mc_command) / sizeof(u32); i++)
    > + ((u32 *)resp)[i] = __raw_readl(&((u32 *)portal)[i]);
    >
    > - return status;
    > + return mc_cmd_hdr_read_status(resp);
    > }
    >
    > /**
    >

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