On 06/06/16 06:40, Shanker Donthineni wrote:
> This patch adds the two handy helper functions for reading and writing
> ITS BASERn register.
>
> Signed-off-by: Shanker Donthineni <shank...@codeaurora.org>
> ---
> drivers/irqchip/irq-gic-v3-its.c | 32 +++++++++++++++++++++++++-------
> 1 file changed, 25 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3-its.c
> b/drivers/irqchip/irq-gic-v3-its.c
> index 5eb1f9e..6392c82 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -56,13 +56,14 @@ struct its_collection {
> };
>
> /*
> - * The ITS_BASER structure - contains memory information and cached
> - * value of BASER register configuration.
> + * The ITS_BASER structure - contains memory information, cached value
> + * of BASER register configuration and register idx.
> */
> struct its_baser {
> void *base;
> u64 val;
> u32 order;
> + u32 idx;
> };
>
> /*
> @@ -824,6 +825,17 @@ static const char *its_base_type_string[] = {
> [GITS_BASER_TYPE_RESERVED7] = "Reserved (7)",
> };
>
> +static u64 its_read_baser(struct its_node *its, struct its_baser *baser)
> +{
> + return readq_relaxed(its->base + GITS_BASER + (baser->idx << 3));
> +}
> +
> +static void its_write_baser(struct its_node *its, struct its_baser *baser,
> + u64 val)
> +{
> + writeq_relaxed(val, its->base + GITS_BASER + (baser->idx << 3));
> +}
> +
> static void its_free_tables(struct its_node *its)
> {
> int i;
> @@ -863,14 +875,20 @@ static int its_alloc_tables(const char *node_name,
> struct its_node *its)
> its->device_ids = ids;
>
> for (i = 0; i < GITS_BASER_NR_REGS; i++) {
> - u64 val = readq_relaxed(its->base + GITS_BASER + i * 8);
> - u64 type = GITS_BASER_TYPE(val);
> - u64 entry_size = GITS_BASER_ENTRY_SIZE(val);
> + struct its_baser *baser = its->tables + i;
> int order = get_order(psz);
> + u64 val, type, entry_size;
> int alloc_pages;
> u64 tmp;
> void *base;
>
> + /* Record the register index */
> + baser->idx = i;
> +
> + val = its_read_baser(its, baser);
> + type = GITS_BASER_TYPE(val);
> + entry_size = GITS_BASER_ENTRY_SIZE(val);
> +
> if (type == GITS_BASER_TYPE_NONE)
> continue;
>
> @@ -939,8 +957,8 @@ retry_baser:
> val |= alloc_pages - 1;
> its->tables[i].val = val;
>
> - writeq_relaxed(val, its->base + GITS_BASER + i * 8);
> - tmp = readq_relaxed(its->base + GITS_BASER + i * 8);
> + its_write_baser(its, baser, val);
> + tmp = its_read_baser(its, baser);
>
> if ((val ^ tmp) & GITS_BASER_SHAREABILITY_MASK) {
> /*
>
Thanks to this abstraction, I now realize what I really hate about this
idea of caching stuff in the its_baser structure: you end up with
inconsistent data:
- You store something in baser->val
- You write something else using its_write_baser
- You read something else using its_read_baser
We have 3 sets of inconsistent data, and what they mean depends on
the context.
What I'm proposing is that its_write_baser always performs a read back,
and stores that read in baser->val. This gives us a more consistent
view of what's going on (the value we wanted, and what the HW is
actually capable of).
How about something like this, on top of my previous suggestion:
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 520d171..5591441 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -836,6 +836,7 @@ static void its_write_baser(struct its_node *its, struct
its_baser *baser,
{
int idx = baser - its->tables;
writeq_relaxed(val, its->base + GITS_BASER + (idx << 3));
+ baser->val = its_read_baser(its, baser);
}
static int its_setup_baser(struct its_node *its, struct its_baser *baser,
@@ -891,7 +892,7 @@ retry_baser:
}
its_write_baser(its, baser, val);
- tmp = its_read_baser(its, baser);
+ tmp = baser->val;
if ((val ^ tmp) & GITS_BASER_SHAREABILITY_MASK) {
/*
@@ -939,7 +940,6 @@ retry_baser:
baser->order = order;
baser->base = base;
baser->psz = psz;
- baser->val = val;
tmp = indirect ? GITS_LVL1_ENTRY_SIZE : esz;
pr_info("ITS@%pa: allocated %d %s @%lx (%s, esz %d, psz %dK, shr %d)\n",
@@ -968,7 +968,7 @@ static bool its_parse_baser_device(struct its_node *its,
struct its_baser *baser
* table by reading bit at offset '62' after writing '1' to it.
*/
its_write_baser(its, baser, val | GITS_BASER_INDIRECT);
- val = its_read_baser(its, baser);
+ val = baser->val;
indirect = !!(val & GITS_BASER_INDIRECT);
if (indirect) {
Thanks,
M.
--
Jazz is not dead. It just smells funny...
