[Skiboot] [PATCH] vas: Disable VAS/NX-842 on some P9 revisions

[Michael Neuling]

On Fri, 2018-02-09 at 13:40 -0800, Sukadev Bhattiprolu wrote:
> VAS/NX-842 are not functional on some P9 revisions, so disable them
> in hardware and skip creating their device tree nodes.
> 
> Since the intent is to prevent OS from configuring VAS/NX, we remove
> only the platform device nodes but leave the VAS/NX DT nodes under
> xscom (i.e we don't skip add_vas_node() in hdata/spira.c)
> 
> Thanks to input from Michael Ellerman, Michael Neuling.
> 
> Signed-off-by: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
> ---
>  hw/nx.c       |  5 +++++
>  hw/vas.c      | 47 ++++++++++++++++++++++++++++++++++++++++++++---
>  include/vas.h |  1 +
>  3 files changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/nx.c b/hw/nx.c
> index 0f6ff04..784a553 100644
> --- a/hw/nx.c
> +++ b/hw/nx.c
> @@ -24,6 +24,7 @@
>  #include <chip.h>
>  #include <xscom-p9-regs.h>
>  #include <phys-map.h>
> +#include <vas.h>
>  #include <p9_stop_api.H>
>  
>  static void p9_darn_init(void)
> @@ -110,6 +111,10 @@ void nx_p9_rng_late_init(void)
>  static void nx_init_one(struct dt_node *node)
>  {
>  	nx_create_rng_node(node);
> +
> +	if (vas_nx_disabled())
> +		return;
> +
>  	nx_create_crypto_node(node);
>  	nx_create_compress_node(node);
>  }
> diff --git a/hw/vas.c b/hw/vas.c
> index fb5a1e7..6362f7e 100644
> --- a/hw/vas.c
> +++ b/hw/vas.c
> @@ -69,6 +69,36 @@ static int vas_scom_write(struct proc_chip *chip, uint64_t
> reg, uint64_t val)
>  	return rc;
>  }
>  
> +/*
> + * VAS and hence, NX-842 are disabled in following POWER9 revisions:
> + *
> + *	- Nimbus DD1.X, DD2.01, DD2.1
> + *	- Cumulus DD1.0
> + *
> + * Return true for those revisions. Return false for others.
> + */
> +__attrconst inline bool vas_nx_disabled(void)

Minor nit, can you make this vax_nx_enabled() and change the sex throughout the
code.

A disabled call returning false hurts my head. :-)

> +{
> +	uint32_t pvr;
> +	int major, minor;
> +	struct proc_chip *chip;
> +
> +	chip = next_chip(NULL);
> +
> +	pvr = mfspr(SPR_PVR);
> +	major = PVR_VERS_MAJ(pvr);
> +	minor = PVR_VERS_MIN(pvr);
> +
> +	switch (chip->type) {
> +	case PROC_CHIP_P9_NIMBUS:
> +		return (major < 2 || (major == 2 && minor <= 1));
> +	case PROC_CHIP_P9_CUMULUS:
> +		return (major == 1 && minor == 0);
> +	default:
> +		return false;
> +	}
> +}
> +
>  /* Interface for NX - make sure VAS is fully initialized first */
>  __attrconst inline uint64_t vas_get_hvwc_mmio_bar(const int chipid)
>  {
> @@ -110,6 +140,9 @@ static int init_north_ctl(struct proc_chip *chip)
>  	return vas_scom_write(chip, VAS_MISC_N_CTL, val);
>  }
>  
> +/*
> + * Ensure paste instructions are not accepted and MMIO BARs are disabled.
> + */
>  static inline int reset_north_ctl(struct proc_chip *chip)
>  {
>  	return vas_scom_write(chip, VAS_MISC_N_CTL, 0ULL);
> @@ -399,7 +432,7 @@ static void disable_vas_inst(struct dt_node *np)
>  /*
>   * Initialize one VAS instance
>   */
> -static int init_vas_inst(struct dt_node *np)
> +static int init_vas_inst(struct dt_node *np, bool disabled)
>  {
>  	uint32_t vas_id;
>  	uint64_t xscom_base;
> @@ -411,6 +444,11 @@ static int init_vas_inst(struct dt_node *np)
>  
>  	chip->vas = alloc_vas(chip->id, vas_id, xscom_base);
>  
> +	if (disabled) {
> +		reset_north_ctl(chip);
> +		return 0;
> +	}
> +
>  	if (alloc_init_wcbs(chip))
>  		return -1;
>  
> @@ -429,17 +467,20 @@ static int init_vas_inst(struct dt_node *np)
>  
>  void vas_init()
>  {
> +	bool disabled;
>  	struct dt_node *np;
>  
>  	if (proc_gen != proc_gen_p9)
>  		return;
>  
> +	disabled = vas_nx_disabled();
> +
>  	dt_for_each_compatible(dt_root, np, "ibm,power9-vas-x") {
> -		if (init_vas_inst(np))
> +		if (init_vas_inst(np, disabled))
>  			goto out;
>  	}
>  
> -	vas_initialized = 1;
> +	vas_initialized = !disabled;
>  	return;
>  
>  out:
> diff --git a/include/vas.h b/include/vas.h
> index 6bc2a1c..2e37908 100644
> --- a/include/vas.h
> +++ b/include/vas.h
> @@ -37,6 +37,7 @@
>   */
>  
>  extern void vas_init(void);
> +extern __attrconst bool vas_nx_disabled(void);
>  extern __attrconst uint64_t vas_get_hvwc_mmio_bar(const int chipid);
>  extern __attrconst uint64_t vas_get_wcbs_bar(int chipid);
>