[v3,2/8] mailbox: arm_mhu: add driver for ARM MHU controller

Message ID 1420802889-4041-1-git-send-email-Vincent.Yang@tw.fujitsu.com
State New
Headers show

Commit Message

Vincent Yang Jan. 9, 2015, 11:28 a.m.
From: Jassi Brar <jaswinder.singh@linaro.org>

Add driver for the ARM Message-Handling-Unit (MHU).

Signed-off-by: Andy Green <andy.green@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Vincent Yang <Vincent.Yang@tw.fujitsu.com>
Signed-off-by: Tetsuya Nuriya <nuriya.tetsuya@jp.fujitsu.com>
---
 .../devicetree/bindings/mailbox/arm-mhu.txt        |  33 ++++
 drivers/mailbox/Kconfig                            |   7 +
 drivers/mailbox/Makefile                           |   2 +
 drivers/mailbox/arm_mhu.c                          | 212 +++++++++++++++++++++
 4 files changed, 254 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/arm-mhu.txt
 create mode 100644 drivers/mailbox/arm_mhu.c

Comments

Jassi Brar Jan. 9, 2015, 1:19 p.m. | #1
On 9 January 2015 at 18:21, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Fri, Jan 09, 2015 at 07:28:09PM +0800, Vincent Yang wrote:
>> +static irqreturn_t mhu_rx_interrupt(int irq, void *p)
>> +{
>> +     struct mbox_chan *chan = p;
>> +     struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
>> +     u32 val;
>> +
>> +     pr_debug("%s:%d\n", __func__, __LINE__);
>> +     val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
>> +     mbox_chan_received_data(chan, (void *)val);
>> +
>> +     writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);
>> +
>> +     return IRQ_HANDLED;
>
> What if 'val' was zero - is the interrupt still "handled" ?
>
This irq shouldn't fire unless RX_STAT register has some non-zero value.

>> +static int mhu_startup(struct mbox_chan *chan)
>> +{
>> +     struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
>
> Casts from void * are not necessary (repeated many times.)
>
>> +     u32 val;
>> +     int ret;
>> +
>> +     pr_debug("%s:%d\n", __func__, __LINE__);
>> +     val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
>> +     writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);
>> +
>> +     ret = request_irq(mlink->irq, mhu_rx_interrupt,
>> +                       IRQF_SHARED, "mhu_link", chan);
>> +     if (unlikely(ret)) {
>> +             pr_err("Unable to aquire IRQ\n");
>> +             return ret;
>> +     }
>> +
>> +     return 0;
>
> Needlessly complicated, and doesn't need that unlikely().  Also doesn't
> print the reason for failure, and merely printing "Unable to aquire IRQ"
> into the kernel log with no indication what produced it is silly.  You
> have the device struct (via chan->mbox->dev), so using dev_err() is a
> definite possibility and improvement.
>
> I'm sure this can be cleaned up and simplified.
>
>> +static int arm_mhu_probe(struct platform_device *pdev)
>> +{
>> +     int i, err;
>> +     struct arm_mhu *mhu;
>> +     struct resource *res;
>> +     int mhu_reg[3] = {0x0, 0x20, 0x200};
>> +
>> +     /* Allocate memory for device */
>> +     mhu = kzalloc(sizeof(*mhu), GFP_KERNEL);
>> +     if (!mhu)
>> +             return -ENOMEM;
>
> Consider using dev_kzalloc().
>
>> +
>> +     mhu->clk = clk_get(&pdev->dev, "clk");
>
> devm_clk_get().
>
>> +     if (unlikely(IS_ERR(mhu->clk)))
>> +             dev_info(&pdev->dev, "unable to init clock\n");
>> +     else
>> +             clk_prepare_enable(mhu->clk);
>> +
>> +     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     mhu->base = ioremap(res->start, resource_size(res));
>
> That's an oops waiting to happen.  Consider using devm_ioremap_resource()
> which will check for !res.
>
>> +     if (!mhu->base) {
>> +             dev_err(&pdev->dev, "ioremap failed.\n");
>> +             kfree(mhu);
>> +             return -EBUSY;
>> +     }
>> +
>> +     for (i = 0; i < 3; i++) {
>> +             mhu->chan[i].con_priv = &mhu->mlink[i];
>> +             res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
>> +             mhu->mlink[i].irq = res->start;
>> +             mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
>> +             mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + 0x100;
>> +     }
>> +
>> +     mhu->mbox.dev = &pdev->dev;
>> +     mhu->mbox.chans = &mhu->chan[0];
>> +     mhu->mbox.num_chans = 3;
>> +     mhu->mbox.ops = &mhu_ops;
>> +     mhu->mbox.txdone_irq = false;
>> +     mhu->mbox.txdone_poll = true;
>> +     mhu->mbox.txpoll_period = 10;
>> +
>> +     platform_set_drvdata(pdev, mhu);
>> +
>> +     err = mbox_controller_register(&mhu->mbox);
>> +     if (err) {
>> +             dev_err(&pdev->dev, "Failed to register mailboxes %d\n", err);
>> +             iounmap(mhu->base);
>
> You don't clk_put() the clock here.  Using devm_* as suggested above
> means you wouldn't have made this mistake here...
>
>> +             kfree(mhu);
>> +     } else {
>> +             dev_info(&pdev->dev, "ARM MHU Mailbox registered\n");
>> +     }
>> +
>> +     return 0;
>
> Always returns success even if mbox_controller_register() fails?
>
>> +}
>> +
>> +static int arm_mhu_remove(struct platform_device *pdev)
>> +{
>> +     struct arm_mhu *mhu = platform_get_drvdata(pdev);
>> +
>> +     mbox_controller_unregister(&mhu->mbox);
>> +
>> +     iounmap(mhu->base);
>> +
>> +     if (!IS_ERR(mhu->clk))
>> +             clk_disable_unprepare(mhu->clk);
>
> No clk_put() ?  If you used devm_* stuff as suggested above, you wouldn't
> need to...
>
Yes, we should have implemented managed resource allocation. Will do.

Thanks,
Jassi
Jassi Brar Jan. 9, 2015, 3:29 p.m. | #2
On 9 January 2015 at 20:54, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Fri, Jan 09, 2015 at 06:49:12PM +0530, Jassi Brar wrote:
>> On 9 January 2015 at 18:21, Russell King - ARM Linux
>> <linux@arm.linux.org.uk> wrote:
>> > On Fri, Jan 09, 2015 at 07:28:09PM +0800, Vincent Yang wrote:
>> >> +static irqreturn_t mhu_rx_interrupt(int irq, void *p)
>> >> +{
>> >> +     struct mbox_chan *chan = p;
>> >> +     struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
>> >> +     u32 val;
>> >> +
>> >> +     pr_debug("%s:%d\n", __func__, __LINE__);
>> >> +     val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
>> >> +     mbox_chan_received_data(chan, (void *)val);
>> >> +
>> >> +     writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);
>> >> +
>> >> +     return IRQ_HANDLED;
>> >
>> > What if 'val' was zero - is the interrupt still "handled" ?
>> >
>> This irq shouldn't fire unless RX_STAT register has some non-zero value.
>
> You claim this interrupt handler using IRQF_SHARED - what if another user
> of this interrupt gets stuck?  Your handler above will prevent the kernel
> recovering as it will think that you are validly processing the stuck
> interrupt each time.
>
> If it isn't shared, then don't use IRQF_SHARED.
>
> Either way, it is good practice to return IRQ_NONE if there's no work to
> be done.
>
OK, will do.

thanks.

Patch hide | download patch | download mbox

diff --git a/Documentation/devicetree/bindings/mailbox/arm-mhu.txt b/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
new file mode 100644
index 0000000..b1b9888
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/arm-mhu.txt
@@ -0,0 +1,33 @@ 
+ARM MHU Mailbox Driver
+======================
+
+The ARM's Message-Handling-Unit (MHU) is a mailbox controller that has
+3 independent channels/links to communicate with remote processor(s).
+ MHU links are hardwired on a platform. A link raises interrupt for any
+received data. However, there is no specified way of knowing if the sent
+data has been read by the remote. This driver assumes the sender polls
+STAT register and the remote clears it after having read the data.
+
+Mailbox Device Node:
+====================
+
+Required properties:
+--------------------
+- compatible:		Shall be "arm,mbox-mhu"
+- reg:			Contains the mailbox register address range (base
+			address and length)
+- #mbox-cells		Shall be 1
+- interrupts:		Contains the interrupt information corresponding to
+			each of the 3 links of MHU.
+
+Example:
+--------
+
+	mhu: mailbox@2b1f0000 {
+		#mbox-cells = <1>;
+		compatible = "arm,mbox-mhu";
+		reg = <0 0x2b1f0000 0x1000>;
+		interrupts = <0 36 4>,
+			     <0 35 4>,
+			     <0 37 4>;
+	};
diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index c04fed9..9238440 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -6,6 +6,13 @@  menuconfig MAILBOX
 	  signals. Say Y if your platform supports hardware mailboxes.
 
 if MAILBOX
+
+config ARM_MHU
+	tristate "ARM MHU Mailbox"
+	depends on ARM
+	help
+	  Say Y here if you want to build the ARM MHU controller driver
+
 config PL320_MBOX
 	bool "ARM PL320 Mailbox"
 	depends on ARM_AMBA
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index dd412c2..c83791d 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -2,6 +2,8 @@ 
 
 obj-$(CONFIG_MAILBOX)		+= mailbox.o
 
+obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o
+
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
 
 obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o
diff --git a/drivers/mailbox/arm_mhu.c b/drivers/mailbox/arm_mhu.c
new file mode 100644
index 0000000..8d061b6
--- /dev/null
+++ b/drivers/mailbox/arm_mhu.c
@@ -0,0 +1,212 @@ 
+/*
+ * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
+ * Copyright (C) 2015 Linaro Ltd.
+ * Author: Jassi Brar <jaswinder.singh@linaro.org>
+ *
+ * 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, version 2 of the License.
+ *
+ * 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/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/mailbox_controller.h>
+#include <linux/platform_device.h>
+
+#define INTR_STAT_OFS	0x0
+#define INTR_SET_OFS	0x8
+#define INTR_CLR_OFS	0x10
+
+struct mhu_link {
+	unsigned irq;
+	void __iomem *tx_reg;
+	void __iomem *rx_reg;
+};
+
+struct arm_mhu {
+	void __iomem *base;
+	struct clk *clk;
+	struct mhu_link mlink[3];
+	struct mbox_chan chan[3];
+	struct mbox_controller mbox;
+};
+
+static irqreturn_t mhu_rx_interrupt(int irq, void *p)
+{
+	struct mbox_chan *chan = p;
+	struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
+	u32 val;
+
+	pr_debug("%s:%d\n", __func__, __LINE__);
+	val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
+	mbox_chan_received_data(chan, (void *)val);
+
+	writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);
+
+	return IRQ_HANDLED;
+}
+
+static bool mhu_last_tx_done(struct mbox_chan *chan)
+{
+	struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
+	u32 val;
+
+	pr_debug("%s:%d\n", __func__, __LINE__);
+	val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+
+	return (val == 0);
+}
+
+static int mhu_send_data(struct mbox_chan *chan, void *data)
+{
+	struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
+
+	pr_debug("%s:%d\n", __func__, __LINE__);
+	if (!mhu_last_tx_done(chan)) {
+		pr_err("%s:%d Shouldn't have seen the day!\n",
+		       __func__, __LINE__);
+		return -EBUSY;
+	}
+
+	writel_relaxed((u32)data, mlink->tx_reg + INTR_SET_OFS);
+
+	return 0;
+}
+
+static int mhu_startup(struct mbox_chan *chan)
+{
+	struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
+	u32 val;
+	int ret;
+
+	pr_debug("%s:%d\n", __func__, __LINE__);
+	val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+	writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);
+
+	ret = request_irq(mlink->irq, mhu_rx_interrupt,
+			  IRQF_SHARED, "mhu_link", chan);
+	if (unlikely(ret)) {
+		pr_err("Unable to aquire IRQ\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static void mhu_shutdown(struct mbox_chan *chan)
+{
+	struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
+
+	pr_debug("%s:%d\n", __func__, __LINE__);
+	free_irq(mlink->irq, chan);
+}
+
+static struct mbox_chan_ops mhu_ops = {
+	.send_data = mhu_send_data,
+	.startup = mhu_startup,
+	.shutdown = mhu_shutdown,
+	.last_tx_done = mhu_last_tx_done,
+};
+
+static int arm_mhu_probe(struct platform_device *pdev)
+{
+	int i, err;
+	struct arm_mhu *mhu;
+	struct resource *res;
+	int mhu_reg[3] = {0x0, 0x20, 0x200};
+
+	/* Allocate memory for device */
+	mhu = kzalloc(sizeof(*mhu), GFP_KERNEL);
+	if (!mhu)
+		return -ENOMEM;
+
+	mhu->clk = clk_get(&pdev->dev, "clk");
+	if (unlikely(IS_ERR(mhu->clk)))
+		dev_info(&pdev->dev, "unable to init clock\n");
+	else
+		clk_prepare_enable(mhu->clk);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mhu->base = ioremap(res->start, resource_size(res));
+	if (!mhu->base) {
+		dev_err(&pdev->dev, "ioremap failed.\n");
+		kfree(mhu);
+		return -EBUSY;
+	}
+
+	for (i = 0; i < 3; i++) {
+		mhu->chan[i].con_priv = &mhu->mlink[i];
+		res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
+		mhu->mlink[i].irq = res->start;
+		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
+		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + 0x100;
+	}
+
+	mhu->mbox.dev = &pdev->dev;
+	mhu->mbox.chans = &mhu->chan[0];
+	mhu->mbox.num_chans = 3;
+	mhu->mbox.ops = &mhu_ops;
+	mhu->mbox.txdone_irq = false;
+	mhu->mbox.txdone_poll = true;
+	mhu->mbox.txpoll_period = 10;
+
+	platform_set_drvdata(pdev, mhu);
+
+	err = mbox_controller_register(&mhu->mbox);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to register mailboxes %d\n", err);
+		iounmap(mhu->base);
+		kfree(mhu);
+	} else {
+		dev_info(&pdev->dev, "ARM MHU Mailbox registered\n");
+	}
+
+	return 0;
+}
+
+static int arm_mhu_remove(struct platform_device *pdev)
+{
+	struct arm_mhu *mhu = platform_get_drvdata(pdev);
+
+	mbox_controller_unregister(&mhu->mbox);
+
+	iounmap(mhu->base);
+
+	if (!IS_ERR(mhu->clk))
+		clk_disable_unprepare(mhu->clk);
+
+	kfree(mhu);
+	return 0;
+}
+
+static const struct of_device_id arm_mhu_dt_ids[] = {
+	{ .compatible = "arm,mbox-mhu" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, arm_mhu_dt_ids);
+
+static struct platform_driver arm_mhu_driver = {
+	.driver = {
+		.name = "arm_mhu",
+		.of_match_table = arm_mhu_dt_ids,
+	},
+	.probe = arm_mhu_probe,
+	.remove = arm_mhu_remove,
+};
+module_platform_driver(arm_mhu_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ARM MHU Driver");
+MODULE_AUTHOR("Jassi Brar <jassisinghbrar@gmail.com>");