Commit c7995bcb authored by Sven Van Asbroeck's avatar Sven Van Asbroeck Committed by Shawn Guo
Browse files

bus: imx-weim: guard against timing configuration conflicts 



When specifying weim child devices, there is a risk that more than
one timing setting is specified for the same chip select.

The driver cannot support such a configuration.

In case of conflict, this patch will print a warning to the log,
and will ignore the child node in question.

In this example, node acme@1 will be ignored, as it tries to modify
timing settings for CS0:

&weim {
	acme@0 {
		compatible = "acme,whatever";
		reg = <0 0 0x100>;
		fsl,weim-cs-timing = <something>;
	};
	acme@1 {
		compatible = "acme,whatnot";
		reg = <0 0x500 0x100>;
		fsl,weim-cs-timing = <something else>;
	};
};

However in this example, the driver will be happy:

&weim {
        acme@0 {
                compatible = "acme,whatever";
                reg = <0 0 0x100>;
                fsl,weim-cs-timing = <something>;
        };
        acme@1 {
                compatible = "acme,whatnot";
                reg = <0 0x500 0x100>;
                fsl,weim-cs-timing = <something>;
        };
};

Signed-off-by: default avatarSven Van Asbroeck <TheSven73@googlemail.com>
Signed-off-by: default avatarShawn Guo <shawnguo@kernel.org>
parent 8b8cb52a

drivers/bus/imx-weim.c

+32 −3
Original line number Diff line number Diff line
@@ -46,8 +46,18 @@ static const struct imx_weim_devtype imx51_weim_devtype = { 
};



#define MAX_CS_REGS_COUNT	6

#define MAX_CS_COUNT		6

#define OF_REG_SIZE		3



struct cs_timing {

	bool is_applied;

	u32 regs[MAX_CS_REGS_COUNT];

};



struct cs_timing_state {

	struct cs_timing cs[MAX_CS_COUNT];

};



static const struct of_device_id weim_id_table[] = {

	/* i.MX1/21 */

	{ .compatible = "fsl,imx1-weim", .data = &imx1_weim_devtype, },
@@ -112,15 +122,20 @@ err: 
}



/* Parse and set the timing for this device. */

static int __init weim_timing_setup(struct device_node *np, void __iomem *base,

				    const struct imx_weim_devtype *devtype)

static int __init weim_timing_setup(struct device *dev,

				    struct device_node *np, void __iomem *base,

				    const struct imx_weim_devtype *devtype,

				    struct cs_timing_state *ts)

{

	u32 cs_idx, value[MAX_CS_REGS_COUNT];

	int i, ret;

	int reg_idx, num_regs;

	struct cs_timing *cst;



	if (WARN_ON(devtype->cs_regs_count > MAX_CS_REGS_COUNT))

		return -EINVAL;

	if (WARN_ON(devtype->cs_count > MAX_CS_COUNT))

		return -EINVAL;



	ret = of_property_read_u32_array(np, "fsl,weim-cs-timing",

					 value, devtype->cs_regs_count);
@@ -146,10 +161,23 @@ static int __init weim_timing_setup(struct device_node *np, void __iomem *base, 
		if (cs_idx >= devtype->cs_count)

			return -EINVAL;



		/* prevent re-configuring a CS that's already been configured */

		cst = &ts->cs[cs_idx];

		if (cst->is_applied && memcmp(value, cst->regs,

					devtype->cs_regs_count * sizeof(u32))) {

			dev_err(dev, "fsl,weim-cs-timing conflict on %pOF", np);

			return -EINVAL;

		}



		/* set the timing for WEIM */

		for (i = 0; i < devtype->cs_regs_count; i++)

			writel(value[i],

				base + cs_idx * devtype->cs_stride + i * 4);

		if (!cst->is_applied) {

			cst->is_applied = true;

			memcpy(cst->regs, value,

				devtype->cs_regs_count * sizeof(u32));

		}

	}



	return 0;
@@ -163,6 +191,7 @@ static int __init weim_parse_dt(struct platform_device *pdev, 
	const struct imx_weim_devtype *devtype = of_id->data;

	struct device_node *child;

	int ret, have_child = 0;

	struct cs_timing_state ts = {};



	if (devtype == &imx50_weim_devtype) {

		ret = imx_weim_gpr_setup(pdev);
@@ -171,7 +200,7 @@ static int __init weim_parse_dt(struct platform_device *pdev, 
	}



	for_each_available_child_of_node(pdev->dev.of_node, child) {

		ret = weim_timing_setup(child, base, devtype);

		ret = weim_timing_setup(&pdev->dev, child, base, devtype, &ts);

		if (ret)

			dev_warn(&pdev->dev, "%pOF set timing failed.\n",

				child);

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