[GIT PULL 9/9] intel_th: msu: Preserve pre-existing buffer configuration

[Alexander Shishkin]

The MSU configuration registers may contain buffer address/size set by
the BIOS or an external hardware debugger, which may want to take over
tracing from the driver when the driver is not actively tracing.

Preserve these settings when not actively tracing.

Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/hwtracing/intel_th/msu.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index 58dd381debd2..9b6ef4edf09e 100644
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -116,6 +116,8 @@ struct msc {
 	unsigned int		single_wrap : 1;
 	void			*base;
 	dma_addr_t		base_addr;
+	u32			orig_addr;
+	u32			orig_sz;
 
 	/* <0: no buffer, 0: no users, >0: active users */
 	atomic_t		user_count;
@@ -736,6 +738,9 @@ static int msc_configure(struct msc *msc)
 		msc_buffer_clear_hw_header(msc);
 	}
 
+	msc->orig_addr = ioread32(msc->reg_base + REG_MSU_MSC0BAR);
+	msc->orig_sz   = ioread32(msc->reg_base + REG_MSU_MSC0SIZE);
+
 	reg = msc->base_addr >> PAGE_SHIFT;
 	iowrite32(reg, msc->reg_base + REG_MSU_MSC0BAR);
 
@@ -810,8 +815,8 @@ static void msc_disable(struct msc *msc)
 
 	msc->enabled = 0;
 
-	iowrite32(0, msc->reg_base + REG_MSU_MSC0BAR);
-	iowrite32(0, msc->reg_base + REG_MSU_MSC0SIZE);
+	iowrite32(msc->orig_addr, msc->reg_base + REG_MSU_MSC0BAR);
+	iowrite32(msc->orig_sz, msc->reg_base + REG_MSU_MSC0SIZE);
 
 	dev_dbg(msc_dev(msc), "MSCnNWSA: %08x\n",
 		ioread32(msc->reg_base + REG_MSU_MSC0NWSA));
-- 
2.20.1