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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: Sven Van Asbroeck <TheSven73@googlemail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This commit is contained in:
Sven Van Asbroeck 2018-12-17 10:48:00 -05:00 committed by Shawn Guo
parent 8b8cb52af3
commit c7995bcb36
1 changed files with 32 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
drivers/bus/imx-weim.c
View File

@ -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);