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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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