diff mbox

[v4,05/11] VAS: Define helpers for access MMIO regions

Message ID 1490937224-29149-6-git-send-email-sukadev@linux.vnet.ibm.com (mailing list archive)
State Superseded
Headers show

Commit Message

Sukadev Bhattiprolu March 31, 2017, 5:13 a.m. UTC
Define some helper functions to access the MMIO regions. We use these
in a follow-on patches to read/write VAS hardware registers. These
helpers are also used to later issue 'paste' instructions to submit
requests to the NX hardware engines.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
Changelog [v3]:
	- Minor reorg/cleanup of map/unmap functions

Changelog [v2]:
	- Get HVWC, UWC and paste addresses from window->vinst (i.e DT)
	  rather than kernel macros.
---
 arch/powerpc/platforms/powernv/vas-window.c | 126 ++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)

Comments

Benjamin Herrenschmidt April 24, 2017, 6:28 a.m. UTC | #1
On Thu, 2017-03-30 at 22:13 -0700, Sukadev Bhattiprolu wrote:
> +static void *map_mmio_region(char *name, uint64_t start, int len)
> +{
> +       void *map;
> +
> +       if (!request_mem_region(start, len, name)) {
> +               pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
> +                               __func__, start, len);
> +               return NULL;
> +       }
> +
> +       map = __ioremap(start, len, pgprot_val(pgprot_cached(__pgprot(0))));
> +       if (!map) {
> +               pr_devel("%s(): ioremap(0x%llx, %d) failed\n", __func__, start,
> +                               len);
> +               return NULL;
> +       }
> +
> +       return map;
> +}

That's very wrong. I assume this never worked right ?

MMIO regions must be mapped non-cachable. Only the paste region
requires being mapped cachable. Ask Aneesh for a cleaner way of
doing it too while at it.

> +/*
> + * Unmap the MMIO regions for a window.
> + */
> +static void unmap_wc_paste_kaddr(struct vas_window *window)
> +{
> +       int len;

Don't use "wc"... that usually means "write combine".

Cheers,
Ben.
Sukadev Bhattiprolu April 24, 2017, 5:25 p.m. UTC | #2
Benjamin Herrenschmidt [benh@kernel.crashing.org] wrote:
> On Thu, 2017-03-30 at 22:13 -0700, Sukadev Bhattiprolu wrote:
> > +static void *map_mmio_region(char *name, uint64_t start, int len)
> > +{
> > +       void *map;
> > +
> > +       if (!request_mem_region(start, len, name)) {
> > +               pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
> > +                               __func__, start, len);
> > +               return NULL;
> > +       }
> > +
> > +       map = __ioremap(start, len, pgprot_val(pgprot_cached(__pgprot(0))));
> > +       if (!map) {
> > +               pr_devel("%s(): ioremap(0x%llx, %d) failed\n", __func__, start,
> > +                               len);
> > +               return NULL;
> > +       }
> > +
> > +       return map;
> > +}
> 
> That's very wrong. I assume this never worked right ?

Untl recently, only tested on simics and has been working there. On the
hardware, hitting a crash on the first mmio write...
> 
> MMIO regions must be mapped non-cachable. Only the paste region

which maybe due to this :-) Should I change to pgprot_noncached() for the
MMIO writes?

> requires being mapped cachable. Ask Aneesh for a cleaner way of
> doing it too while at it.

Ok.

> 
> > +/*
> > + * Unmap the MMIO regions for a window.
> > + */
> > +static void unmap_wc_paste_kaddr(struct vas_window *window)
> > +{
> > +       int len;
> 
> Don't use "wc"... that usually means "write combine".

Ok.

Thanks,

Sukadev
Benjamin Herrenschmidt April 24, 2017, 11:19 p.m. UTC | #3
On Mon, 2017-04-24 at 10:25 -0700, Sukadev Bhattiprolu wrote:
> which maybe due to this :-) Should I change to pgprot_noncached() for
> the MMIO writes?

Just use normal ioremap().

> > requires being mapped cachable. Ask Aneesh for a cleaner way of
> > doing it too while at it.
diff mbox

Patch

diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index 6156fbe..ec084d2 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -9,9 +9,135 @@ 
 
 #include <linux/types.h>
 #include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/io.h>
 
 #include "vas.h"
 
+/*
+ * Compute the paste address region for the window @window using the
+ * ->win_base_addr and ->win_id_shift we got from device tree.
+ */
+void compute_paste_address(struct vas_window *window, uint64_t *addr, int *len)
+{
+	uint64_t base, shift;
+	int winid;
+
+	base = window->vinst->win_base_addr;
+	shift = window->vinst->win_id_shift;
+	winid = window->winid;
+
+	*addr  = base + (winid << shift);
+	*len = PAGE_SIZE;
+
+	pr_debug("Txwin #%d: Paste addr 0x%llx\n", winid, *addr);
+}
+
+static inline void get_hvwc_mmio_bar(struct vas_window *window,
+			uint64_t *start, int *len)
+{
+	uint64_t pbaddr;
+
+	pbaddr = window->vinst->hvwc_bar_start;
+	*start = pbaddr + window->winid * VAS_HVWC_SIZE;
+	*len = VAS_HVWC_SIZE;
+}
+
+static inline void get_uwc_mmio_bar(struct vas_window *window,
+			uint64_t *start, int *len)
+{
+	uint64_t pbaddr;
+
+	pbaddr = window->vinst->uwc_bar_start;
+	*start = pbaddr + window->winid * VAS_UWC_SIZE;
+	*len = VAS_UWC_SIZE;
+}
+
+static void *map_mmio_region(char *name, uint64_t start, int len)
+{
+	void *map;
+
+	if (!request_mem_region(start, len, name)) {
+		pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
+				__func__, start, len);
+		return NULL;
+	}
+
+	map = __ioremap(start, len, pgprot_val(pgprot_cached(__pgprot(0))));
+	if (!map) {
+		pr_devel("%s(): ioremap(0x%llx, %d) failed\n", __func__, start,
+				len);
+		return NULL;
+	}
+
+	return map;
+}
+
+/*
+ * Unmap the MMIO regions for a window.
+ */
+static void unmap_wc_paste_kaddr(struct vas_window *window)
+{
+	int len;
+	uint64_t busaddr_start;
+
+	if (window->paste_kaddr) {
+		iounmap(window->paste_kaddr);
+		compute_paste_address(window, &busaddr_start, &len);
+		release_mem_region((phys_addr_t)busaddr_start, len);
+		window->paste_kaddr = NULL;
+	}
+
+}
+
+static void unmap_wc_mmio_bars(struct vas_window *window)
+{
+	int len;
+	uint64_t busaddr_start;
+
+	unmap_wc_paste_kaddr(window);
+
+	if (window->hvwc_map) {
+		iounmap(window->hvwc_map);
+		get_hvwc_mmio_bar(window, &busaddr_start, &len);
+		release_mem_region((phys_addr_t)busaddr_start, len);
+		window->hvwc_map = NULL;
+	}
+
+	if (window->uwc_map) {
+		iounmap(window->uwc_map);
+		get_uwc_mmio_bar(window, &busaddr_start, &len);
+		release_mem_region((phys_addr_t)busaddr_start, len);
+		window->uwc_map = NULL;
+	}
+}
+
+/*
+ * Find the Hypervisor Window Context (HVWC) MMIO Base Address Region and the
+ * OS/User Window Context (UWC) MMIO Base Address Region for the given window.
+ * Map these bus addresses and save the mapped kernel addresses in @window.
+ */
+int map_wc_mmio_bars(struct vas_window *window)
+{
+	int len;
+	uint64_t start;
+
+	window->paste_kaddr = window->hvwc_map = window->uwc_map = NULL;
+
+	get_hvwc_mmio_bar(window, &start, &len);
+	window->hvwc_map = map_mmio_region("HVWCM_Window", start, len);
+
+	get_uwc_mmio_bar(window, &start, &len);
+	window->uwc_map = map_mmio_region("UWCM_Window", start, len);
+
+	if (!window->hvwc_map || !window->uwc_map) {
+		unmap_wc_mmio_bars(window);
+		return -1;
+	}
+
+	return 0;
+}
+
 /* stub for now */
 int vas_win_close(struct vas_window *window)
 {