Hi!
Alan Tull writes:
> Supports Altera SOCFPGA bridges:
> * fpga2sdram
> * fpga2hps
> * hps2fpga
> * lwhps2fpga
>
> Allows enabling/disabling the bridges through the FPGA
> Bridge Framework API functions.
>
> The fpga2sdram driver only supports enabling and disabling
> of the ports that been configured early on. This is due to
> a hardware limitation where the read, write, and command
> ports on the fpga2sdram bridge can only be reconfigured
> while there are no transactions to the sdram, i.e. when
> running out of OCRAM before the kernel boots.
>
> Device tree property 'init-val' configures the driver to
> enable or disable the bridge during probe. If the property
> does not exist, the driver will leave the bridge in its
> current state.
>
> Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Matthew Gerlach <mgerlach@xxxxxxxxxx>
> Signed-off-by: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
(...)
> +static inline int _alt_fpga2sdram_enable_set(struct alt_fpga2sdram_data *priv,
> + bool enable)
> +{
> + return regmap_update_bits(priv->sdrctl, ALT_SDR_CTL_FPGAPORTRST_OFST,
> + priv->mask, enable ? priv->mask : 0);
> +}
(...)
> + /* Get f2s bridge configuration saved in handoff register */
> + regmap_read(sysmgr, SYSMGR_ISWGRP_HANDOFF3, &priv->mask);
> +
Could you maybe add some documentation about this implicit information
shared between a bootloader and this driver?
I understand why you do this, but there must be a better way than
depending on something some bootloader wrote in some undocumented
register, no?
The documentation just says:
"These registers are used to store handoff infomation between the
preloader and the OS. These 8 registers can be used to store any
information. The contents of these registers have no impact on the
state of the HPS hardware"
If it is already agreed upon, that a bridge-enable property is okay,
why not add a port-enable property, too?
Regards,
Steffen Trumtrar
--
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