mowgli: Limit slot1 to Gen3 by default

From: LuluTHSu <Lulu_Su@wistron.com>

Refer to the spec. of mowgli, limit the slot to Gen3 speed.
For mowgli platform spec.

Cc: skiboot-stable@lists.ozlabs.org
Signed-off-by: LuluTHSu <Lulu_Su@wistron.com>
---
 hw/phb4.c                 | 21 +++++++++++++++++++++
 include/phb4.h            |  1 +
 platforms/astbmc/mowgli.c | 16 ++++++++++++++++
 3 files changed, 38 insertions(+)

On 10/29/20 4:53 PM, Lulu Su wrote:
> From: LuluTHSu <Lulu_Su@wistron.com>
> 
> Refer to the spec. of mowgli, limit the slot to Gen3 speed.
> For mowgli platform spec.

Lulu,

General process is to post patch to skiboot mailing list and get it accepted in 
upstream. Then backport patch to applicable stable branches.

I dont see this patch posted to upstream. Can you please post it to skiboot 
mailing list?

-Vasant

> 
> Cc: skiboot-stable@lists.ozlabs.org
> Signed-off-by: LuluTHSu <Lulu_Su@wistron.com>
> ---
>   hw/phb4.c                 | 21 +++++++++++++++++++++
>   include/phb4.h            |  1 +
>   platforms/astbmc/mowgli.c | 16 ++++++++++++++++
>   3 files changed, 38 insertions(+)
> 
> diff --git a/hw/phb4.c b/hw/phb4.c
> index 17a233f..de10bb0 100644
> --- a/hw/phb4.c
> +++ b/hw/phb4.c
> @@ -2991,6 +2991,27 @@ static unsigned int phb4_get_max_link_speed(struct phb4 *p, struct dt_node *np)
>   	return max_link_speed;
>   }
> 
> +/*
> + * Has the same effect as the ibm,max-link-speed property.
> + * i.e. sets the default link speed, while allowing NVRAM
> + * overrides, etc to still take effect.
> + */
> +void phb4_set_dt_max_link_speed(struct phb4 *p, int new_max)
> +{
> +	uint64_t scr;
> +	int max;
> +
> +	/* take into account nvram settings, etc */
> +	if (pcie_max_link_speed)
> +		max = pcie_max_link_speed;
> +	else
> +		max = new_max;
> +	
> +	scr = phb4_read_reg(p, PHB_PCIE_SCR);
> +	scr = SETFIELD(PHB_PCIE_SCR_MAXLINKSPEED, scr, max);
> +	phb4_write_reg(p, PHB_PCIE_SCR, scr);
> +}
> +
>   static void phb4_assert_perst(struct pci_slot *slot, bool assert)
>   {
>   	struct phb4 *p = phb_to_phb4(slot->phb);
> diff --git a/include/phb4.h b/include/phb4.h
> index abba2d9..47a46b7 100644
> --- a/include/phb4.h
> +++ b/include/phb4.h
> @@ -259,4 +259,5 @@ static inline int phb4_get_opal_id(unsigned int chip_id, unsigned int index)
> 
>   void phb4_pec2_dma_engine_realloc(struct phb4 *p);
> 
> +void phb4_set_dt_max_link_speed(struct phb4 *p, int new_max);
>   #endif /* __PHB4_H */
> diff --git a/platforms/astbmc/mowgli.c b/platforms/astbmc/mowgli.c
> index 9bfe7a4..0246bff 100644
> --- a/platforms/astbmc/mowgli.c
> +++ b/platforms/astbmc/mowgli.c
> @@ -12,6 +12,8 @@
>   #include <psi.h>
>   #include <npu-regs.h>
>   #include <secvar.h>
> +#include <pci.h>
> +#include <phb4.h>
> 
>   #include "astbmc.h"
> 
> @@ -71,6 +73,19 @@ static int mowgli_secvar_init(void)
>   	return secvar_main(secboot_tpm_driver, edk2_compatible_v1);
>   }
> 
> +/*
> + * Limit PHB0/(pec0) to gen3 speeds.
> + */
> +static void mowgli_setup_phb(struct phb *phb, unsigned int __unused index)
> +{
> +	struct phb4 *p = phb_to_phb4(phb);
> +
> + 	if (p->pec == 0) {
> +		phb4_set_dt_max_link_speed(p, 3);
> +		prlog(PR_DEBUG, "Mowgli: Force the PHB%d Speed to Gen3.\n", p->pec);
> +	}
> +}
> +
>   DECLARE_PLATFORM(mowgli) = {
>   	.name			= "Mowgli",
>   	.probe			= mowgli_probe,
> @@ -80,6 +95,7 @@ DECLARE_PLATFORM(mowgli) = {
>   	.bmc			= &bmc_plat_ast2500_openbmc,
>   	.pci_get_slot_info	= slot_table_get_slot_info,
>   	.pci_probe_complete	= check_all_slot_table,
> +	.pci_setup_phb 		= mowgli_setup_phb,
>   	.cec_power_down         = astbmc_ipmi_power_down,
>   	.cec_reboot             = astbmc_ipmi_reboot,
>   	.elog_commit		= ipmi_elog_commit,
>

On 10/29/20 4:53 PM, Lulu Su wrote:
> From: LuluTHSu <Lulu_Su@wistron.com>
> 
> Refer to the spec. of mowgli, limit the slot to Gen3 speed.
> For mowgli platform spec.
> 

AFAIK Mowgli will use skiboot v6.7. I guess we don't need to backport this to 
stable tree.

Let me know if you still need this patch in stable tree.

-Vasant