On 18.06.21 10:09, Steffen Trumtrar wrote:
> To make changes to the SDRAM controller effective, the APPLYCFG bit must
> be set after programming the bitstream to the FPGA. This has to be done
> without any SDRAM usage. Therefore copy the function to execute to the
> OCRAM and execute it from there.
>
> Signed-off-by: Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
> ---
> +extern void socfpga_sdram_apply_static_cfg(void __iomem *sdrctrlgrp);
> +extern void socfpga_sdram_apply_static_cfg_end(void *);
> +
> struct fpgamgr {
> struct firmware_handler fh;
> struct device_d dev;
> @@ -353,6 +359,9 @@ static int fpgamgr_program_finish(struct firmware_handler *fh)
> {
> struct fpgamgr *mgr = container_of(fh, struct fpgamgr, fh);
> int status;
> + unsigned int func_size = &socfpga_sdram_apply_static_cfg_end -
> + &socfpga_sdram_apply_static_cfg;
This is wildly undefined. Kernel users of fncpy I looked at as well as the fncpy
documentation itself suggest doing the arithmetic in assembly instead. See below.
> + void (*ocram_func)(void __iomem *ocram_base);
>
> /* Ensure the FPGA entering config done */
> status = fpgamgr_program_poll_cd(mgr);
> @@ -382,6 +391,18 @@ static int fpgamgr_program_finish(struct firmware_handler *fh)
> return status;
> }
>
> + remap_range((void *)CYCLONE5_OCRAM_ADDRESS, PAGE_SIZE, MAP_CACHED);
> +
> + dev_dbg(&mgr->dev, "Setting APPLYCFG bit...\n");
> +
> + ocram_func = fncpy((void __iomem *)CYCLONE5_OCRAM_ADDRESS,
> + &socfpga_sdram_apply_static_cfg, func_size);
> +
> + sync_caches_for_execution();
> +
> + ocram_func((void __iomem *) (CYCLONE5_SDR_ADDRESS +
> + SDR_CTRLGRP_STATICCFG_ADDRESS));
> +
> return 0;
> }
>
> diff --git a/drivers/firmware/socfpga_sdr.S b/drivers/firmware/socfpga_sdr.S
> new file mode 100644
> index 000000000000..d634d6362722
> --- /dev/null
> +++ b/drivers/firmware/socfpga_sdr.S
> @@ -0,0 +1,17 @@
> +#include <linux/linkage.h>
> +
> + .arch armv7-a
> + .arm
> +
> +/*
> + * r0 : sdram controller staticcfg
> + */
> +
> +ENTRY(socfpga_sdram_apply_static_cfg)
> + push {ip,lr}
> + ldr r1, [r0]
> + orr r1, r1, #8
> + str r1, [r0]
> + pop {ip,pc}
> + .align
> +ENTRY(socfpga_sdram_apply_static_cfg_end)
Alternative:
ENDPROC(socfpga_sdram_apply_static_cfg)
ENTRY(socfpga_sdram_apply_static_sz)
.word . - socfpga_sdram_apply_static_cfg
And then size is accessible from C with
extern const u32 socfpga_sdram_apply_static_cfg_sz;
This makes for a clean disassembly and avoids the undefined
behavior above.
--
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