Re: [PATCH v2 1/3] ipmi: add an Aspeed BT IPMI BMC driver

[LABBE Corentin <clabbe.montjoie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hello

I have some minor comment below:

On Fri, Sep 16, 2016 at 12:39:25PM +0200, Cédric Le Goater wrote:
> From: Alistair Popple <alistair-Y4h6yKqj69EXC2x5gXVKYQ@public.gmane.org>
> 
> This patch adds a simple device driver to expose the iBT interface on
> Aspeed SOCs (AST2400 and AST2500) as a character device. Such SOCs are
> commonly used as BMCs (BaseBoard Management Controllers) and this
> driver implements the BMC side of the BT interface.
> 
> The BT (Block Transfer) interface is used to perform in-band IPMI
> communication between a host and its BMC. Entire messages are buffered
> before sending a notification to the other end, host or BMC, that
> there is data to be read. Usually, the host emits requests and the BMC
> responses but the specification provides a mean for the BMC to send
> SMS Attention (BMC-to-Host attention or System Management Software
> attention) messages.
> 
> For this purpose, the driver introduces a specific ioctl on the
> device: 'BT_BMC_IOCTL_SMS_ATN' that can be used by the system running
> on the BMC to signal the host of such an event.
> 
> The device name defaults to '/dev/ipmi-bt-host'
> 
> Signed-off-by: Alistair Popple <alistair-Y4h6yKqj69EXC2x5gXVKYQ@public.gmane.org>
> Signed-off-by: Jeremy Kerr <jk-mnsaURCQ41sdnm+yROfE0A@public.gmane.org>
> Signed-off-by: Joel Stanley <joel-U3u1mxZcP9KHXe+LvDLADg@public.gmane.org>
> [clg: - checkpatch fixes
>       - added a devicetree binding documentation
>       - replace 'bt_host' by 'bt_bmc' to reflect that the driver is
>         the BMC side of the IPMI BT interface
>       - renamed the device to 'ipmi-bt-host'
>       - introduced a temporary buffer to copy_{to,from}_user
>       - used platform_get_irq()
>       - moved the driver under drivers/char/ipmi/ but kept it as a misc
>         device
>       - changed the compatible cell to "aspeed,ast2400-bt-bmc"
> ]
> Signed-off-by: Cédric Le Goater <clg-Bxea+6Xhats@public.gmane.org>
> ---
> 
>  Changes since v1:
> 
>  - replace 'bt_host' by 'bt_bmc' to reflect that the driver is
>    the BMC side of the IPMI BT interface
>  - renamed the device to 'ipmi-bt-host'
>  - introduced a temporary buffer to copy_{to,from}_user
>  - used platform_get_irq()
>  - moved the driver under drivers/char/ipmi/ but kept it as a misc
>    device
>  - changed the compatible cell to "aspeed,ast2400-bt-bmc"
> 
>  .../bindings/char/ipmi/aspeed,ast2400-bt-bmc.txt   |  23 +
>  drivers/Makefile                                   |   2 +-
>  drivers/char/ipmi/Kconfig                          |   7 +
>  drivers/char/ipmi/Makefile                         |   1 +
>  drivers/char/ipmi/bt-bmc.c                         | 486 +++++++++++++++++++++
>  include/uapi/linux/Kbuild                          |   1 +
>  include/uapi/linux/bt-bmc.h                        |  18 +
>  7 files changed, 537 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/devicetree/bindings/char/ipmi/aspeed,ast2400-bt-bmc.txt
>  create mode 100644 drivers/char/ipmi/bt-bmc.c
>  create mode 100644 include/uapi/linux/bt-bmc.h
> 
> diff --git a/Documentation/devicetree/bindings/char/ipmi/aspeed,ast2400-bt-bmc.txt b/Documentation/devicetree/bindings/char/ipmi/aspeed,ast2400-bt-bmc.txt
> new file mode 100644
> index 000000000000..fbbacd958240
> --- /dev/null

[..]

> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/errno.h>
> +#include <linux/poll.h>
> +#include <linux/sched.h>
> +#include <linux/spinlock.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/miscdevice.h>
> +#include <linux/timer.h>
> +#include <linux/jiffies.h>
> +#include <linux/bt-bmc.h>

Please sort them in alphabetical order, some of them seems not needed also (like spinlock.h)

> +
> +/*
> + * This is a BMC device used to communicate to the host
> + */
> +#define DEVICE_NAME	"ipmi-bt-host"
> +
> +#define BT_IO_BASE	0xe4
> +#define BT_IRQ		10
> +
> +#define BT_CR0		0x0
> +#define   BT_CR0_IO_BASE		16
> +#define   BT_CR0_IRQ			12
> +#define   BT_CR0_EN_CLR_SLV_RDP		0x8
> +#define   BT_CR0_EN_CLR_SLV_WRP		0x4
> +#define   BT_CR0_ENABLE_IBT		0x1
> +#define BT_CR1		0x4
> +#define   BT_CR1_IRQ_H2B	0x01
> +#define   BT_CR1_IRQ_HBUSY	0x40
> +#define BT_CR2		0x8
> +#define   BT_CR2_IRQ_H2B	0x01
> +#define   BT_CR2_IRQ_HBUSY	0x40
> +#define BT_CR3		0xc
> +#define BT_CTRL		0x10
> +#define   BT_CTRL_B_BUSY		0x80
> +#define   BT_CTRL_H_BUSY		0x40
> +#define   BT_CTRL_OEM0			0x20
> +#define   BT_CTRL_SMS_ATN		0x10
> +#define   BT_CTRL_B2H_ATN		0x08
> +#define   BT_CTRL_H2B_ATN		0x04
> +#define   BT_CTRL_CLR_RD_PTR		0x02
> +#define   BT_CTRL_CLR_WR_PTR		0x01
> +#define BT_BMC2HOST	0x14
> +#define BT_INTMASK	0x18
> +#define   BT_INTMASK_B2H_IRQEN		0x01
> +#define   BT_INTMASK_B2H_IRQ		0x02
> +#define   BT_INTMASK_BMC_HWRST		0x80

Why to use 3 space after some define ?

[..]

> +
> +#define BT_BMC_BUFFER_SIZE 256

Put this define with others

[..]

> +
> +static irqreturn_t bt_bmc_irq(int irq, void *arg)
> +{
> +	struct bt_bmc *bt_bmc = arg;
> +	uint32_t reg;

u32 is prefered other uint32_t, do you have run checkpatch --strict ?

> +
> +	reg = ioread32(bt_bmc->base + BT_CR2);
> +	reg &= BT_CR2_IRQ_H2B | BT_CR2_IRQ_HBUSY;
> +	if (!reg)
> +		return IRQ_NONE;
> +
> +	/* ack pending IRQs */
> +	iowrite32(reg, bt_bmc->base + BT_CR2);
> +
> +	wake_up(&bt_bmc->queue);
> +	return IRQ_HANDLED;
> +}
> +
> +static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
> +		struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	uint32_t reg;
> +	int rc;
> +
> +	bt_bmc->irq = platform_get_irq(pdev, 0);
> +	if (!bt_bmc->irq)
> +		return -ENODEV;
> +
> +	rc = devm_request_irq(dev, bt_bmc->irq, bt_bmc_irq, IRQF_SHARED,
> +			DEVICE_NAME, bt_bmc);
> +	if (rc < 0) {
> +		dev_warn(dev, "Unable to request IRQ %d\n", bt_bmc->irq);
> +		bt_bmc->irq = 0;
> +		return rc;
> +	}
> +
> +	/* Configure IRQs on the bmc clearing the H2B and HBUSY bits;
> +	 * H2B will be asserted when the bmc has data for us; HBUSY
> +	 * will be cleared (along with B2H) when we can write the next
> +	 * message to the BT buffer
> +	 */

This comment doesnt have the style recommended for new driver.

> +	reg = ioread32(bt_bmc->base + BT_CR1);
> +	reg |= BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY;
> +	iowrite32(reg, bt_bmc->base + BT_CR1);
> +
> +	return 0;
> +}
> +
> +static int bt_bmc_probe(struct platform_device *pdev)
> +{
> +	struct bt_bmc *bt_bmc;
> +	struct device *dev;
> +	struct resource *res;
> +	int rc;
> +
> +	if (!pdev || !pdev->dev.of_node)
> +		return -ENODEV;
> +
> +	dev = &pdev->dev;
> +	dev_info(dev, "Found bt bmc device\n");
> +
> +	bt_bmc = devm_kzalloc(dev, sizeof(*bt_bmc), GFP_KERNEL);
> +	if (!bt_bmc)
> +		return -ENOMEM;
> +
> +	dev_set_drvdata(&pdev->dev, bt_bmc);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(dev, "Unable to find resources\n");
> +		rc = -ENXIO;
> +		goto out_free;
> +	}
> +
> +	bt_bmc->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (!bt_bmc->base) {
> +		rc = -ENOMEM;
> +		goto out_free;
> +	}
> +
> +	init_waitqueue_head(&bt_bmc->queue);
> +
> +	bt_bmc->miscdev.minor	= MISC_DYNAMIC_MINOR,
> +	bt_bmc->miscdev.name	= DEVICE_NAME,
> +	bt_bmc->miscdev.fops	= &bt_bmc_fops,
> +	bt_bmc->miscdev.parent = dev;
> +	rc = misc_register(&bt_bmc->miscdev);
> +	if (rc) {
> +		dev_err(dev, "Unable to register device\n");

Be more precise by saying misc device

> +		goto out_unmap;
> +	}
> +
> +	bt_bmc_config_irq(bt_bmc, pdev);
> +
> +	if (bt_bmc->irq) {
> +		dev_info(dev, "Using IRQ %d\n", bt_bmc->irq);
> +	} else {
> +		dev_info(dev, "No IRQ; using timer\n");
> +		setup_timer(&bt_bmc->poll_timer, poll_timer,
> +				(unsigned long)bt_bmc);
> +		bt_bmc->poll_timer.expires = jiffies + msecs_to_jiffies(10);
> +		add_timer(&bt_bmc->poll_timer);
> +	}
> +
> +	iowrite32((BT_IO_BASE << BT_CR0_IO_BASE) |
> +		  (BT_IRQ << BT_CR0_IRQ) |
> +		  BT_CR0_EN_CLR_SLV_RDP |
> +		  BT_CR0_EN_CLR_SLV_WRP |
> +		  BT_CR0_ENABLE_IBT,
> +		  bt_bmc->base + BT_CR0);
> +
> +	clr_b_busy(bt_bmc);
> +
> +	return 0;
> +
> +out_unmap:
> +	devm_iounmap(&pdev->dev, bt_bmc->base);

Why do you use devm_iounmap/devm_kfree since the interest with devm_ functions is that all cleanup is done when driver is removed.

> +
> +out_free:
> +	devm_kfree(dev, bt_bmc);
> +	return rc;

I think you should remove the space after this return

Regards

Corentin Labbe
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html