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[PATCH 05/16] drivers/fsi: Add fake master driver

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  [PATCH 05/16] drivers/fsi: Add fake master driver Chris Bostic <christopher.lee.bostic@gmail.com> - 2016-12-07 01:20 +0100
    Re: [PATCH 05/16] drivers/fsi: Add fake master driver Mark Rutland <mark.rutland@arm.com> - 2016-12-07 13:20 +0100
      Re: [PATCH 05/16] drivers/fsi: Add fake master driver Jeremy Kerr <jk@ozlabs.org> - 2016-12-08 00:30 +0100

#1537371 — [PATCH 05/16] drivers/fsi: Add fake master driver

From: Jeremy Kerr <jk@ozlabs.org>

For debugging, add a fake master driver, that only supports reads,
returning a fixed set of data.

Includes changes from Chris Bostic <cbostic@us.ibm.com>.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
---
 drivers/fsi/Kconfig           | 10 +++++
 drivers/fsi/Makefile          |  1 +
 drivers/fsi/fsi-master-fake.c | 95 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 drivers/fsi/fsi-master-fake.c

diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig
index 04c1a0e..f065dbe 100644
--- a/drivers/fsi/Kconfig
+++ b/drivers/fsi/Kconfig
@@ -9,4 +9,14 @@ config FSI
 	---help---
 	  FSI - the FRU Support Interface - is a simple bus for low-level
 	  access to POWER-based hardware.
+
+if FSI
+
+config FSI_MASTER_FAKE
+	tristate "Fake FSI master"
+	depends on FSI
+	---help---
+	This option enables a fake FSI master driver for debugging.
+endif
+
 endmenu
diff --git a/drivers/fsi/Makefile b/drivers/fsi/Makefile
index db0e5e7..847c00c 100644
--- a/drivers/fsi/Makefile
+++ b/drivers/fsi/Makefile
@@ -1,2 +1,3 @@
 
 obj-$(CONFIG_FSI) += fsi-core.o
+obj-$(CONFIG_FSI_MASTER_FAKE) += fsi-master-fake.o
diff --git a/drivers/fsi/fsi-master-fake.c b/drivers/fsi/fsi-master-fake.c
new file mode 100644
index 0000000..b42fe5b
--- /dev/null
+++ b/drivers/fsi/fsi-master-fake.c
@@ -0,0 +1,95 @@
+/*
+ * Fake FSI master driver for FSI development
+ *
+ * Copyright (C) IBM Corporation 2016
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+
+#include "fsi-master.h"
+
+static const uint8_t data[] = {
+	0xc0, 0x02, 0x08, 0x03,	/* chip id */
+	0x80, 0x01, 0x11, 0x00,	/* peek */
+	0x80, 0x01, 0x20, 0x3e,	/* slave */
+	0x00, 0x01, 0x10, 0xa5,	/* i2c */
+};
+
+
+static int fsi_master_fake_read(struct fsi_master *_master, int link,
+		uint8_t slave, uint32_t addr, void *val, size_t size)
+{
+	if (link != 0)
+		return -ENODEV;
+
+	if (addr + size > sizeof(data))
+		memset(val, 0, size);
+	else
+		memcpy(val, data + addr, size);
+
+	return 0;
+}
+
+static int fsi_master_fake_write(struct fsi_master *_master, int link,
+		uint8_t slave, uint32_t addr, const void *val, size_t size)
+{
+	if (link != 0)
+		return -ENODEV;
+
+	return -EACCES;
+}
+
+static int fsi_master_fake_probe(struct platform_device *pdev)
+{
+	struct fsi_master *master;
+
+	master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
+	if (!master)
+		return -ENOMEM;
+
+	master->dev = &pdev->dev;
+	master->n_links = 1;
+	master->read = fsi_master_fake_read;
+	master->write = fsi_master_fake_write;
+
+	return fsi_master_register(master);
+}
+
+static const struct of_device_id fsi_master_fake_match[] = {
+	{ .compatible = "ibm,fsi-master-fake" },
+	{ },
+};
+
+static struct platform_driver fsi_master_fake_driver = {
+	.driver = {
+		.name		= "fsi-master-fake",
+		.of_match_table	= fsi_master_fake_match,
+	},
+	.probe	= fsi_master_fake_probe,
+};
+
+static int __init fsi_master_fake_init(void)
+{
+	struct device_node *np;
+
+	platform_driver_register(&fsi_master_fake_driver);
+
+	for_each_compatible_node(np, NULL, "ibm,fsi-master-fake")
+		of_platform_device_create(np, NULL, NULL);
+
+	return 0;
+}
+
+module_init(fsi_master_fake_init);
-- 
1.8.2.2

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#1537716

On Tue, Dec 06, 2016 at 06:14:26PM -0600, Chris Bostic wrote:
> From: Jeremy Kerr <jk@ozlabs.org>
> 
> For debugging, add a fake master driver, that only supports reads,
> returning a fixed set of data.

> +config FSI_MASTER_FAKE
> +	tristate "Fake FSI master"
> +	depends on FSI
> +	---help---
> +	This option enables a fake FSI master driver for debugging.
> +endif

> +static const struct of_device_id fsi_master_fake_match[] = {
> +	{ .compatible = "ibm,fsi-master-fake" },
> +	{ },
> +};

NAK.

DT should be treated as an ABI, and should describe the HW explicitly.
This makes no sense. This is also missing a binding document.

Have your module take a module parameter allowing you to bind it to
arbitrary devices, or do something like what PCI does where you can
bind/unbind arbitrary drivers to devices using sysfs.

> +
> +static struct platform_driver fsi_master_fake_driver = {
> +	.driver = {
> +		.name		= "fsi-master-fake",
> +		.of_match_table	= fsi_master_fake_match,
> +	},
> +	.probe	= fsi_master_fake_probe,
> +};
> +
> +static int __init fsi_master_fake_init(void)
> +{
> +	struct device_node *np;
> +
> +	platform_driver_register(&fsi_master_fake_driver);
> +
> +	for_each_compatible_node(np, NULL, "ibm,fsi-master-fake")
> +		of_platform_device_create(np, NULL, NULL);

As a general note, please use for_each_matching_node in situations like
this. That way you can reuse your existing of_device_id table, and not
reproduce the string.

That said, this is not necessary. The platform driver has an
of_match_table, so presumes the parent bus registers children, and hence
they should already have platform devices.

Thanks,
Mark.

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#1538173

Hi Mark & Chris,

> On Tue, Dec 06, 2016 at 06:14:26PM -0600, Chris Bostic wrote:
>> From: Jeremy Kerr <jk@ozlabs.org>
>>
>> For debugging, add a fake master driver, that only supports reads,
>> returning a fixed set of data.
> 
>> +config FSI_MASTER_FAKE
>> +	tristate "Fake FSI master"
>> +	depends on FSI
>> +	---help---
>> +	This option enables a fake FSI master driver for debugging.
>> +endif
> 
>> +static const struct of_device_id fsi_master_fake_match[] = {
>> +	{ .compatible = "ibm,fsi-master-fake" },
>> +	{ },
>> +};
> 
> NAK.
> 
> DT should be treated as an ABI, and should describe the HW explicitly.
> This makes no sense. This is also missing a binding document.
> 
> Have your module take a module parameter allowing you to bind it to
> arbitrary devices, or do something like what PCI does where you can
> bind/unbind arbitrary drivers to devices using sysfs.

This driver is purely for testing the FSI engine scan code; we could
probably just drop this patch since I suspect that it's no longer useful
(now that we have an actual master driver).

If we do want to keep it though, I'd say we remove the device tree
dependency; all this is doing at the moment is triggering the ->probe,
and there are better ways to do that.

Cheers,


Jeremy

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