diff mbox series

[v3] memory: dfl-emif: add the DFL EMIF private feature driver

Message ID 1600666280-25651-2-git-send-email-yilun.xu@intel.com
State New
Headers show
Series [v3] memory: dfl-emif: add the DFL EMIF private feature driver | expand

Commit Message

Xu Yilun Sept. 21, 2020, 5:31 a.m. UTC
This driver is for the EMIF private feature implemented under FPGA
Device Feature List (DFL) framework. It is used to expose memory
interface status information as well as memory clearing control.

The purpose of memory clearing block is to zero out all private memory
when FPGA is to be reprogrammed. This gives users a reliable method to
prevent potential data leakage.

Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
---
v2: Adjust the position of this driver in Kconfig.
    Improves the name of the Kconfig option.
    Change the include dfl-bus.h to dfl.h, cause the previous patchset
     renames the file.
    Some minor fixes and comment improvement.
v3: Adjust the position of the driver in Makefile.
---
 .../ABI/testing/sysfs-bus-dfl-devices-emif         |  25 +++
 drivers/memory/Kconfig                             |   9 +
 drivers/memory/Makefile                            |   2 +
 drivers/memory/dfl-emif.c                          | 207 +++++++++++++++++++++
 4 files changed, 243 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
 create mode 100644 drivers/memory/dfl-emif.c

Comments

Krzysztof Kozlowski Sept. 21, 2020, 7:23 a.m. UTC | #1
On Mon, Sep 21, 2020 at 01:31:20PM +0800, Xu Yilun wrote:
> This driver is for the EMIF private feature implemented under FPGA
> Device Feature List (DFL) framework. It is used to expose memory
> interface status information as well as memory clearing control.
> 
> The purpose of memory clearing block is to zero out all private memory
> when FPGA is to be reprogrammed. This gives users a reliable method to
> prevent potential data leakage.
> 
> Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> ---
> v2: Adjust the position of this driver in Kconfig.
>     Improves the name of the Kconfig option.
>     Change the include dfl-bus.h to dfl.h, cause the previous patchset
>      renames the file.
>     Some minor fixes and comment improvement.
> v3: Adjust the position of the driver in Makefile.
> ---
>  .../ABI/testing/sysfs-bus-dfl-devices-emif         |  25 +++
>  drivers/memory/Kconfig                             |   9 +
>  drivers/memory/Makefile                            |   2 +
>  drivers/memory/dfl-emif.c                          | 207 +++++++++++++++++++++
>  4 files changed, 243 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
>  create mode 100644 drivers/memory/dfl-emif.c
> 

Hi Moritz,

Since this depends on dfl patches, I would need a stable tag with them
or you can take it directly:
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>

Best regards,
Krzysztof
Moritz Fischer Sept. 21, 2020, 8:31 p.m. UTC | #2
Hi Krzysztof,

On Mon, Sep 21, 2020 at 09:23:11AM +0200, Krzysztof Kozlowski wrote:
> On Mon, Sep 21, 2020 at 01:31:20PM +0800, Xu Yilun wrote:
> > This driver is for the EMIF private feature implemented under FPGA
> > Device Feature List (DFL) framework. It is used to expose memory
> > interface status information as well as memory clearing control.
> > 
> > The purpose of memory clearing block is to zero out all private memory
> > when FPGA is to be reprogrammed. This gives users a reliable method to
> > prevent potential data leakage.
> > 
> > Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> > Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> > ---
> > v2: Adjust the position of this driver in Kconfig.
> >     Improves the name of the Kconfig option.
> >     Change the include dfl-bus.h to dfl.h, cause the previous patchset
> >      renames the file.
> >     Some minor fixes and comment improvement.
> > v3: Adjust the position of the driver in Makefile.
> > ---
> >  .../ABI/testing/sysfs-bus-dfl-devices-emif         |  25 +++
> >  drivers/memory/Kconfig                             |   9 +
> >  drivers/memory/Makefile                            |   2 +
> >  drivers/memory/dfl-emif.c                          | 207 +++++++++++++++++++++
> >  4 files changed, 243 insertions(+)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> >  create mode 100644 drivers/memory/dfl-emif.c
> > 
> 
> Hi Moritz,
> 
> Since this depends on dfl patches, I would need a stable tag with them
> or you can take it directly:
> Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
> 
> Best regards,
> Krzysztof

The FPGA patches go through Greg's tree. For the time being it's
probably easiest if I take the changes through my tree once Greg pulled
my tree.

Do you have any feedback to better handle this sort of subsystem
spanning changesets for me?

Thanks,
Moritz
Krzysztof Kozlowski Sept. 21, 2020, 8:46 p.m. UTC | #3
WhOn Mon, 21 Sep 2020 at 22:31, Moritz Fischer <mdf@kernel.org> wrote:
>
> Hi Krzysztof,
>
> On Mon, Sep 21, 2020 at 09:23:11AM +0200, Krzysztof Kozlowski wrote:
> > On Mon, Sep 21, 2020 at 01:31:20PM +0800, Xu Yilun wrote:
> > > This driver is for the EMIF private feature implemented under FPGA
> > > Device Feature List (DFL) framework. It is used to expose memory
> > > interface status information as well as memory clearing control.
> > >
> > > The purpose of memory clearing block is to zero out all private memory
> > > when FPGA is to be reprogrammed. This gives users a reliable method to
> > > prevent potential data leakage.
> > >
> > > Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> > > Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> > > ---
> > > v2: Adjust the position of this driver in Kconfig.
> > >     Improves the name of the Kconfig option.
> > >     Change the include dfl-bus.h to dfl.h, cause the previous patchset
> > >      renames the file.
> > >     Some minor fixes and comment improvement.
> > > v3: Adjust the position of the driver in Makefile.
> > > ---
> > >  .../ABI/testing/sysfs-bus-dfl-devices-emif         |  25 +++
> > >  drivers/memory/Kconfig                             |   9 +
> > >  drivers/memory/Makefile                            |   2 +
> > >  drivers/memory/dfl-emif.c                          | 207 +++++++++++++++++++++
> > >  4 files changed, 243 insertions(+)
> > >  create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> > >  create mode 100644 drivers/memory/dfl-emif.c
> > >
> >
> > Hi Moritz,
> >
> > Since this depends on dfl patches, I would need a stable tag with them
> > or you can take it directly:
> > Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
> >
> > Best regards,
> > Krzysztof
>
> The FPGA patches go through Greg's tree. For the time being it's
> probably easiest if I take the changes through my tree once Greg pulled
> my tree.

Yes.

>
> Do you have any feedback to better handle this sort of subsystem
> spanning changesets for me?

The easiest through a separate branch. Assuming that such need for
sharing patches is known.

If the patches touch generic things, which could be used by other
drivers/subsystems, or if it is known that there will be someone
depending on them, the easiest is to put them on separate branch which
you later merge into your for-next. You send to Greg your for-next. If
these patches are needed by someone else, e.g. me, you prepare a tag
on them and send a pull request with that tag. I pull it and send
these (and only these!) along with other patches. No duplication of
commits, only two merges.

Recent example was here:
https://lore.kernel.org/lkml/20200819191722.GA38371@sirena.org.uk/
where Mark Brown wanted these through his tree, but later work on
Samsung ARM depended on them.

Best regards,
Krzysztof
Moritz Fischer Sept. 22, 2020, 3:17 a.m. UTC | #4
Hi Krzysztof,

On Mon, Sep 21, 2020 at 10:46:45PM +0200, Krzysztof Kozlowski wrote:
> WhOn Mon, 21 Sep 2020 at 22:31, Moritz Fischer <mdf@kernel.org> wrote:
> >
> > Hi Krzysztof,
> >
> > On Mon, Sep 21, 2020 at 09:23:11AM +0200, Krzysztof Kozlowski wrote:
> > > On Mon, Sep 21, 2020 at 01:31:20PM +0800, Xu Yilun wrote:
> > > > This driver is for the EMIF private feature implemented under FPGA
> > > > Device Feature List (DFL) framework. It is used to expose memory
> > > > interface status information as well as memory clearing control.
> > > >
> > > > The purpose of memory clearing block is to zero out all private memory
> > > > when FPGA is to be reprogrammed. This gives users a reliable method to
> > > > prevent potential data leakage.
> > > >
> > > > Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> > > > Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> > > > ---
> > > > v2: Adjust the position of this driver in Kconfig.
> > > >     Improves the name of the Kconfig option.
> > > >     Change the include dfl-bus.h to dfl.h, cause the previous patchset
> > > >      renames the file.
> > > >     Some minor fixes and comment improvement.
> > > > v3: Adjust the position of the driver in Makefile.
> > > > ---
> > > >  .../ABI/testing/sysfs-bus-dfl-devices-emif         |  25 +++
> > > >  drivers/memory/Kconfig                             |   9 +
> > > >  drivers/memory/Makefile                            |   2 +
> > > >  drivers/memory/dfl-emif.c                          | 207 +++++++++++++++++++++
> > > >  4 files changed, 243 insertions(+)
> > > >  create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
> > > >  create mode 100644 drivers/memory/dfl-emif.c
> > > >
> > >
> > > Hi Moritz,
> > >
> > > Since this depends on dfl patches, I would need a stable tag with them
> > > or you can take it directly:
> > > Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
> > >
> > > Best regards,
> > > Krzysztof
> >
> > The FPGA patches go through Greg's tree. For the time being it's
> > probably easiest if I take the changes through my tree once Greg pulled
> > my tree.
> 
> Yes.
> 
> >
> > Do you have any feedback to better handle this sort of subsystem
> > spanning changesets for me?
> 
> The easiest through a separate branch. Assuming that such need for
> sharing patches is known.
> 
> If the patches touch generic things, which could be used by other
> drivers/subsystems, or if it is known that there will be someone
> depending on them, the easiest is to put them on separate branch which
> you later merge into your for-next. You send to Greg your for-next. If
> these patches are needed by someone else, e.g. me, you prepare a tag
> on them and send a pull request with that tag. I pull it and send
> these (and only these!) along with other patches. No duplication of
> commits, only two merges.
> 
> Recent example was here:
> https://lore.kernel.org/lkml/20200819191722.GA38371@sirena.org.uk/
> where Mark Brown wanted these through his tree, but later work on
> Samsung ARM depended on them.
> 
> Best regards,
> Krzysztof

Appreciate the explanation, that makes sense. Thanks for taking the
time. I'll do this moving forward.

Cheers,
Moritz
diff mbox series

Patch

diff --git a/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif b/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
new file mode 100644
index 0000000..56f97dc
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-dfl-devices-emif
@@ -0,0 +1,25 @@ 
+What:		/sys/bus/dfl/devices/dfl_dev.X/infX_cal_fail
+Date:		Sep 2020
+KernelVersion:	5.10
+Contact:	Xu Yilun <yilun.xu@intel.com>
+Description:	Read-only. It indicates if the calibration failed on this
+		memory interface. "1" for calibration failure, "0" for OK.
+		Format: %u
+
+What:		/sys/bus/dfl/devices/dfl_dev.X/infX_init_done
+Date:		Sep 2020
+KernelVersion:	5.10
+Contact:	Xu Yilun <yilun.xu@intel.com>
+Description:	Read-only. It indicates if the initialization completed on
+		this memory interface. "1" for initialization complete, "0"
+		for not yet.
+		Format: %u
+
+What:		/sys/bus/dfl/devices/dfl_dev.X/infX_clear
+Date:		Sep 2020
+KernelVersion:	5.10
+Contact:	Xu Yilun <yilun.xu@intel.com>
+Description:	Write-only. Writing "1" to this file will zero out all memory
+		data in this memory interface. Writing of other values is
+		invalid.
+		Format: %u
diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
index 00e013b..2495bc4 100644
--- a/drivers/memory/Kconfig
+++ b/drivers/memory/Kconfig
@@ -137,6 +137,15 @@  config TI_EMIF_SRAM
 	  sequence so this driver provides several relocatable PM functions
 	  for the SoC PM code to use.
 
+config FPGA_DFL_EMIF
+	tristate "FPGA DFL EMIF Driver"
+	depends on FPGA_DFL && HAS_IOMEM
+	help
+	  This driver is for the EMIF private feature implemented under
+	  FPGA Device Feature List (DFL) framework. It is used to expose
+	  memory interface status information as well as memory clearing
+	  control.
+
 config MVEBU_DEVBUS
 	bool "Marvell EBU Device Bus Controller"
 	default y if PLAT_ORION
diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
index e71cf7b..bc7663e 100644
--- a/drivers/memory/Makefile
+++ b/drivers/memory/Makefile
@@ -28,6 +28,8 @@  obj-$(CONFIG_STM32_FMC2_EBI)	+= stm32-fmc2-ebi.o
 obj-$(CONFIG_SAMSUNG_MC)	+= samsung/
 obj-$(CONFIG_TEGRA_MC)		+= tegra/
 obj-$(CONFIG_TI_EMIF_SRAM)	+= ti-emif-sram.o
+obj-$(CONFIG_FPGA_DFL_EMIF)	+= dfl-emif.o
+
 ti-emif-sram-objs		:= ti-emif-pm.o ti-emif-sram-pm.o
 
 AFLAGS_ti-emif-sram-pm.o	:=-Wa,-march=armv7-a
diff --git a/drivers/memory/dfl-emif.c b/drivers/memory/dfl-emif.c
new file mode 100644
index 0000000..0799d53
--- /dev/null
+++ b/drivers/memory/dfl-emif.c
@@ -0,0 +1,207 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DFL device driver for EMIF private feature
+ *
+ * Copyright (C) 2020 Intel Corporation, Inc.
+ *
+ */
+#include <linux/bitfield.h>
+#include <linux/errno.h>
+#include <linux/fpga/dfl.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#define FME_FEATURE_ID_EMIF		0x9
+
+#define EMIF_STAT			0x8
+#define EMIF_STAT_INIT_DONE_SFT		0
+#define EMIF_STAT_CALC_FAIL_SFT		8
+#define EMIF_STAT_CLEAR_BUSY_SFT	16
+#define EMIF_CTRL			0x10
+#define EMIF_CTRL_CLEAR_EN_SFT		0
+#define EMIF_CTRL_CLEAR_EN_MSK		GENMASK_ULL(3, 0)
+
+#define EMIF_POLL_INVL			10000 /* us */
+#define EMIF_POLL_TIMEOUT		5000000 /* us */
+
+struct dfl_emif {
+	struct device *dev;
+	void __iomem *base;
+	spinlock_t lock;	/* Serialises access to EMIF_CTRL reg */
+};
+
+struct emif_attr {
+	struct device_attribute attr;
+	u32 shift;
+	u32 index;
+};
+
+#define to_emif_attr(dev_attr) \
+	container_of(dev_attr, struct emif_attr, attr)
+
+static ssize_t emif_state_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct emif_attr *eattr = to_emif_attr(attr);
+	struct dfl_emif *de = dev_get_drvdata(dev);
+	u64 val;
+
+	val = readq(de->base + EMIF_STAT);
+
+	return sprintf(buf, "%u\n",
+		       !!(val & BIT_ULL(eattr->shift + eattr->index)));
+}
+
+static ssize_t emif_clear_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct emif_attr *eattr = to_emif_attr(attr);
+	struct dfl_emif *de = dev_get_drvdata(dev);
+	u64 clear_busy_msk, clear_en_msk, val;
+	void __iomem *base = de->base;
+
+	if (!sysfs_streq(buf, "1"))
+		return -EINVAL;
+
+	clear_busy_msk = BIT_ULL(EMIF_STAT_CLEAR_BUSY_SFT + eattr->index);
+	clear_en_msk = BIT_ULL(EMIF_CTRL_CLEAR_EN_SFT + eattr->index);
+
+	spin_lock(&de->lock);
+	/* The CLEAR_EN field is WO, but other fields are RW */
+	val = readq(base + EMIF_CTRL);
+	val &= ~EMIF_CTRL_CLEAR_EN_MSK;
+	val |= clear_en_msk;
+	writeq(val, base + EMIF_CTRL);
+	spin_unlock(&de->lock);
+
+	if (readq_poll_timeout(base + EMIF_STAT, val,
+			       !(val & clear_busy_msk),
+			       EMIF_POLL_INVL, EMIF_POLL_TIMEOUT)) {
+		dev_err(de->dev, "timeout, fail to clear\n");
+		return -ETIMEDOUT;
+	}
+
+	return count;
+}
+
+#define emif_state_attr(_name, _shift, _index)				\
+	struct emif_attr emif_attr_##inf##_index##_##_name =		\
+		{ .attr = __ATTR(inf##_index##_##_name, 0444,		\
+				 emif_state_show, NULL),		\
+		  .shift = (_shift), .index = (_index) }
+
+#define emif_clear_attr(_index)						\
+	struct emif_attr emif_attr_##inf##_index##_clear =		\
+		{ .attr = __ATTR(inf##_index##_clear, 0200,		\
+				 NULL, emif_clear_store),		\
+		  .index = (_index) }
+
+emif_state_attr(init_done, EMIF_STAT_INIT_DONE_SFT, 0);
+emif_state_attr(init_done, EMIF_STAT_INIT_DONE_SFT, 1);
+emif_state_attr(init_done, EMIF_STAT_INIT_DONE_SFT, 2);
+emif_state_attr(init_done, EMIF_STAT_INIT_DONE_SFT, 3);
+
+emif_state_attr(cal_fail, EMIF_STAT_CALC_FAIL_SFT, 0);
+emif_state_attr(cal_fail, EMIF_STAT_CALC_FAIL_SFT, 1);
+emif_state_attr(cal_fail, EMIF_STAT_CALC_FAIL_SFT, 2);
+emif_state_attr(cal_fail, EMIF_STAT_CALC_FAIL_SFT, 3);
+
+emif_clear_attr(0);
+emif_clear_attr(1);
+emif_clear_attr(2);
+emif_clear_attr(3);
+
+static struct attribute *dfl_emif_attrs[] = {
+	&emif_attr_inf0_init_done.attr.attr,
+	&emif_attr_inf0_cal_fail.attr.attr,
+	&emif_attr_inf0_clear.attr.attr,
+
+	&emif_attr_inf1_init_done.attr.attr,
+	&emif_attr_inf1_cal_fail.attr.attr,
+	&emif_attr_inf1_clear.attr.attr,
+
+	&emif_attr_inf2_init_done.attr.attr,
+	&emif_attr_inf2_cal_fail.attr.attr,
+	&emif_attr_inf2_clear.attr.attr,
+
+	&emif_attr_inf3_init_done.attr.attr,
+	&emif_attr_inf3_cal_fail.attr.attr,
+	&emif_attr_inf3_clear.attr.attr,
+
+	NULL,
+};
+
+static umode_t dfl_emif_visible(struct kobject *kobj,
+				struct attribute *attr, int n)
+{
+	struct dfl_emif *de = dev_get_drvdata(kobj_to_dev(kobj));
+	struct emif_attr *eattr = container_of(attr, struct emif_attr,
+					       attr.attr);
+	u64 val;
+
+	/*
+	 * This device supports upto 4 memory interfaces, but not all
+	 * interfaces are used on different platforms. The read out value of
+	 * CLEAN_EN field (which is a bitmap) could tell how many interfaces
+	 * are available.
+	 */
+	val = FIELD_GET(EMIF_CTRL_CLEAR_EN_MSK, readq(de->base + EMIF_CTRL));
+
+	return (val & BIT_ULL(eattr->index)) ? attr->mode : 0;
+}
+
+static const struct attribute_group dfl_emif_group = {
+	.is_visible = dfl_emif_visible,
+	.attrs = dfl_emif_attrs,
+};
+
+static const struct attribute_group *dfl_emif_groups[] = {
+	&dfl_emif_group,
+	NULL,
+};
+
+static int dfl_emif_probe(struct dfl_device *dfl_dev)
+{
+	struct device *dev = &dfl_dev->dev;
+	struct dfl_emif *de;
+
+	de = devm_kzalloc(dev, sizeof(*de), GFP_KERNEL);
+	if (!de)
+		return -ENOMEM;
+
+	de->base = devm_ioremap_resource(dev, &dfl_dev->mmio_res);
+	if (IS_ERR(de->base))
+		return PTR_ERR(de->base);
+
+	de->dev = dev;
+	spin_lock_init(&de->lock);
+	dev_set_drvdata(dev, de);
+
+	return 0;
+}
+
+static const struct dfl_device_id dfl_emif_ids[] = {
+	{ FME_ID, FME_FEATURE_ID_EMIF },
+	{ }
+};
+MODULE_DEVICE_TABLE(dfl, dfl_emif_ids);
+
+static struct dfl_driver dfl_emif_driver = {
+	.drv	= {
+		.name       = "dfl-emif",
+		.dev_groups = dfl_emif_groups,
+	},
+	.id_table = dfl_emif_ids,
+	.probe   = dfl_emif_probe,
+};
+module_dfl_driver(dfl_emif_driver);
+
+MODULE_DESCRIPTION("DFL EMIF driver");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");