Re: [PATCH v2 5/6] mailbox: Add generic mechanism for testing Mailbox Controllers

[Lee Jones]

On Mon, 10 Aug 2015, Jassi Brar wrote:

> On Mon, Jul 27, 2015 at 3:14 PM, Lee Jones <lee.jones@xxxxxxxxxx> wrote:
> > This particular Client implementation uses shared memory in order
> > to pass messages between Mailbox users; however, it can be easily
> > hacked to support any type of Controller.
> >
> > Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
> > ---
> >  drivers/mailbox/Kconfig        |   7 ++
> >  drivers/mailbox/Makefile       |   2 +
> >  drivers/mailbox/mailbox-test.c | 210 +++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 219 insertions(+)
> >  create mode 100644 drivers/mailbox/mailbox-test.c
> >
> > diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> > index 2cc4c39..7720bde 100644
> > --- a/drivers/mailbox/Kconfig
> > +++ b/drivers/mailbox/Kconfig
> > @@ -77,4 +77,11 @@ config STI_MBOX
> >           Mailbox implementation for STMicroelectonics family chips with
> >           hardware for interprocessor communication.
> >
> > +config MAILBOX_TEST
> > +       tristate "Mailbox Test Client"
> > +       depends on OF
> > +       help
> > +         Test client to help with testing new Controller driver
> > +         implementations.
> > +
> >  endif
> > diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> > index 7cb4766..92435ef 100644
> > --- a/drivers/mailbox/Makefile
> > +++ b/drivers/mailbox/Makefile
> > @@ -2,6 +2,8 @@
> >
> >  obj-$(CONFIG_MAILBOX)          += mailbox.o
> >
> > +obj-$(CONFIG_MAILBOX_TEST)     += mailbox-test.o
> > +
> >  obj-$(CONFIG_ARM_MHU)  += arm_mhu.o
> >
> >  obj-$(CONFIG_PL320_MBOX)       += pl320-ipc.o
> > diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c
> > new file mode 100644
> > index 0000000..10bfe3a
> > --- /dev/null
> > +++ b/drivers/mailbox/mailbox-test.c
> > @@ -0,0 +1,210 @@
> > +/*
> > + * Copyright (C) 2015 ST Microelectronics
> > + *
> > + * Author: Lee Jones <lee.jones@xxxxxxxxxx>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + */
> > +
> > +#include <linux/debugfs.h>
> > +#include <linux/err.h>
> > +#include <linux/kernel.h>
> > +#include <linux/mailbox_client.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +#include <linux/uaccess.h>
> > +
> > +#define MBOX_MAX_MSG_LEN 128
> > +
> > +static struct dentry *root_debugfs_dir;
> > +
> > +struct mbox_test_device {
> > +       struct device           *dev;
> > +       struct mbox_chan        *tx_channel;
> > +       struct mbox_chan        *rx_channel;
> > +       void __iomem            *mmio;
> > +
> > +};
> > +
> > +static ssize_t mbox_test_write(struct file *filp,
> > +                              const char __user *userbuf,
> > +                              size_t count, loff_t *ppos)
> > +{
> > +       struct mbox_test_device *tdev = filp->private_data;
> > +       char *message;
> > +       int ret;
> > +
> > +       if (count > MBOX_MAX_MSG_LEN) {
> > +               dev_err(tdev->dev,
> > +                       "Message length %d greater than max allowed %d\n",
> > +                       count, MBOX_MAX_MSG_LEN);
> > +               return -EINVAL;
> > +       }
> > +
> > +       message = kzalloc(count, GFP_KERNEL);
> > +       if (!message)
> > +               return -ENOMEM;
> > +
> > +       ret = copy_from_user(message, userbuf, count);
> > +       if (ret)
> > +               return -EFAULT;
> > +
> > +       print_hex_dump(KERN_ERR, "Client: Sending: ", DUMP_PREFIX_ADDRESS,
> > +                      16, 1, message, 16, true);
> > +
> > +       ret = mbox_send_message(tdev->tx_channel, message);
> > +       if (ret < 0)
> > +               dev_err(tdev->dev, "Failed to send message via mailbox\n");
> > +
> > +       kfree(message);
> > +
> > +       return ret < 0 ? ret : count;
> > +}
> > +
> > +static const struct file_operations mbox_test_ops = {
> > +       .write  = mbox_test_write,
> > +       .open   = simple_open,
> > +       .llseek = generic_file_llseek,
> > +};
> > +
> > +static int mbox_test_add_debugfs(struct platform_device *pdev,
> > +                                struct mbox_test_device *tdev)
> > +{
> > +       if (!debugfs_initialized())
> > +               return 0;
> > +
> > +       root_debugfs_dir = debugfs_create_dir("mailbox", NULL);
> > +       if (!root_debugfs_dir) {
> > +               dev_err(&pdev->dev, "Failed to create Mailbox debugfs\n");
> > +               return -EINVAL;
> > +       }
> > +
> > +       debugfs_create_file("send-message", 0200, root_debugfs_dir,
> > +                           tdev, &mbox_test_ops);
> > +
> > +       return 0;
> > +}
> > +
> > +static void mbox_test_receive_message(struct mbox_client *client, void *message)
> > +{
> > +       struct mbox_test_device *tdev = dev_get_drvdata(client->dev);
> > +
> > +       if (!tdev->mmio) {
> > +               dev_info(tdev->dev, "Client: Recived something [read mmio]\n");
> > +               return;
> > +       }
> > +
> > +       print_hex_dump(KERN_ERR, "Client: from co-proc: ", DUMP_PREFIX_ADDRESS,
> > +                      16, 1, tdev->mmio, MBOX_MAX_MSG_LEN, true);
> > +}
> > +
> > +static void mbox_test_prepare_message(struct mbox_client *client, void *message)
> > +{
> > +       struct mbox_test_device *tdev = dev_get_drvdata(client->dev);
> > +
> > +       if (tdev->mmio)
> > +               memcpy(tdev->mmio, message, MBOX_MAX_MSG_LEN);
> >
> This is unlikely to work. Those platforms that need to send a 2 part
> message, they do :
> (a) Signal/Command/Target code via some controller register (via
> mbox_send_message).
> (b) Setup the payload in Shared-Memory (via tx_prepare).
> 
> This test driver assumes both are the same. I think you have to
> declare something like

This driver assumes that the framework will call client->tx_prepare()
first, which satisfies (b).  It then assumes controller->send_data()
will be invoked, which will send the platform specific
signal/command/target code, which then satisfies (a).

In what way does it assume they are the same?

> struct mbox_test_message { /* same for TX and RX */
>           unsigned sig_len;
>           void *signal;               /* rx/tx via mailbox api */
>           unsigned pl_len;
>           void *payload;           /* rx/tx via shared-memory */
> };

How do you think this should be set and use these?

> > +
> > +static void mbox_test_message_sent(struct mbox_client *client,
> > +                                  void *message, int r)
> > +{
> > +       if (r)
> > +               dev_warn(client->dev,
> > +                        "Client: Message could not be sent: %d\n", r);
> > +       else
> > +               dev_info(client->dev,
> > +                        "Client: Message sent\n");
> > +}
> > +
> > +static struct mbox_chan *
> > +mbox_test_request_channel(struct platform_device *pdev, const char *name)
> > +{
> > +       struct mbox_client *client;
> > +
> > +       client = devm_kzalloc(&pdev->dev, sizeof(*client), GFP_KERNEL);
> > +       if (!client)
> > +               return ERR_PTR(-ENOMEM);
> > +
> > +       client->dev             = &pdev->dev;
> > +       client->rx_callback     = mbox_test_receive_message;
> > +       client->tx_prepare      = mbox_test_prepare_message;
> > +       client->tx_done         = mbox_test_message_sent;
> > +       client->tx_block        = true;
> > +       client->knows_txdone    = false;
> > +       client->tx_tout         = 500;
> > +
> > +       return mbox_request_channel_byname(client, name);
> > +}
> > +
> > +static int mbox_test_probe(struct platform_device *pdev)
> > +{
> > +       struct mbox_test_device *tdev;
> > +       struct resource *res;
> > +       int ret;
> > +
> > +       tdev = devm_kzalloc(&pdev->dev, sizeof(*tdev), GFP_KERNEL);
> > +       if (!tdev)
> > +               return -ENOMEM;
> > +
> > +       /* It's okay for MMIO to be NULL */
> > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       tdev->mmio = devm_ioremap_resource(&pdev->dev, res);
> > +       if (IS_ERR(tdev->mmio))
> > +               tdev->mmio = NULL;
> > +
> > +       tdev->tx_channel = mbox_test_request_channel(pdev, "tx");
> > +       if (IS_ERR(tdev->tx_channel))
> > +               return PTR_ERR(tdev->tx_channel);
> > +
> > +       tdev->rx_channel = mbox_test_request_channel(pdev, "rx");
> > +       if (IS_ERR(tdev->rx_channel))
> > +               return PTR_ERR(tdev->rx_channel);
> > +
> Should it really fail on TX or RX only clients?

Good question.  Probably not, but I guess we'd need a flag for that.

> It takes write from userspace but shouldn't it also provide data
> received to the userspace?

Currently we only print the returning message.  If you want me to put
it in a userspace file too, that's not an issue.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org â Open source software for ARM SoCs
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