linux-kernel - [PATCH] coresight-stm: support mmapping channel regions with mmio

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Message-Id: <1465870615-10215-1-git-send-email-zhang.chunyan@linaro.org>
Date:	Tue, 14 Jun 2016 10:16:55 +0800
From:	Chunyan Zhang <zhang.chunyan@...aro.org>
To:	mathieu.poirier@...aro.org
Cc:	zhang.lyra@...il.com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Al.Grant@....com
Subject: [PATCH] coresight-stm: support mmapping channel regions with mmio_addr

CoreSight STM device allows direct mapping of the channel regions to
userspace for zero-copy writing. To support this ability, the STM
freamwork has provided a hook 'mmio_addr', this patch just implemented
this hook for CoreSight STM.

This patch also added an item into 'channel_space' to save the start
physical address of channel region which mmap operation needs to know.

Signed-off-by: Chunyan Zhang <zhang.chunyan@...aro.org>
---
 drivers/hwtracing/coresight/coresight-stm.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
index 73be58a..4e70478 100644
--- a/drivers/hwtracing/coresight/coresight-stm.c
+++ b/drivers/hwtracing/coresight/coresight-stm.c
@@ -109,6 +109,7 @@ module_param_named(
  */
 struct channel_space {
 	void __iomem		*base;
+	phys_addr_t		phys;
 	unsigned long		*guaranteed;
 };
 
@@ -356,6 +357,23 @@ static void stm_generic_unlink(struct stm_data *stm_data,
 	stm_disable(drvdata->csdev);
 }
 
+static phys_addr_t
+stm_mmio_addr(struct stm_data *stm_data, unsigned int master,
+	      unsigned int channel, unsigned int nr_chans)
+{
+	struct stm_drvdata *drvdata = container_of(stm_data,
+						   struct stm_drvdata, stm);
+	phys_addr_t addr;
+
+	addr = drvdata->chs.phys + channel * BYTES_PER_CHANNEL;
+
+	if (offset_in_page(addr) ||
+	    offset_in_page(nr_chans * BYTES_PER_CHANNEL))
+		return 0;
+
+	return addr;
+}
+
 static long stm_generic_set_options(struct stm_data *stm_data,
 				    unsigned int master,
 				    unsigned int channel,
@@ -761,7 +779,9 @@ static void stm_init_generic_data(struct stm_drvdata *drvdata)
 	drvdata->stm.sw_end = 1;
 	drvdata->stm.hw_override = true;
 	drvdata->stm.sw_nchannels = drvdata->numsp;
+	drvdata->stm.sw_mmiosz = BYTES_PER_CHANNEL;
 	drvdata->stm.packet = stm_generic_packet;
+	drvdata->stm.mmio_addr = stm_mmio_addr;
 	drvdata->stm.link = stm_generic_link;
 	drvdata->stm.unlink = stm_generic_unlink;
 	drvdata->stm.set_options = stm_generic_set_options;
@@ -808,6 +828,7 @@ static int stm_probe(struct amba_device *adev, const struct amba_id *id)
 	ret = stm_get_resource_byname(np, "stm-stimulus-base", &ch_res);
 	if (ret)
 		return ret;
+	drvdata->chs.phys = ch_res.start;
 
 	base = devm_ioremap_resource(dev, &ch_res);
 	if (IS_ERR(base))
-- 
1.9.1