Re: [PATCH v3 3/3] bus: imx-weim: guard against timing configuration conflicts
From: Shawn Guo <shawnguo@kernel.org>
Date: 2018-12-11 06:20:41
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On Thu, Dec 06, 2018 at 02:26:33PM -0500, Sven Van Asbroeck wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- drivers/bus/imx-weim.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-)diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c index 5452d22d1bd8..dfe74b8c512a 100644 --- a/drivers/bus/imx-weim.c +++ b/drivers/bus/imx-weim.c@@ -46,8 +46,18 @@ static const struct imx_weim_devtype imx51_weim_devtype = { }; #define MAX_CS_REGS_COUNT 6 +#define MAX_CS_REGS 6
The macro name can easily confuse people with existing MAX_CS_REGS_COUNT. By its meaning, I guess MAX_CS_COUNT should be more accurate?
quoted hunk ↗ jump to hunk
#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_REGS]; +}; + static const struct of_device_id weim_id_table[] = { /* i.MX1/21 */ { .compatible = "fsl,imx1-weim", .data = &imx1_weim_devtype, },@@ -112,11 +122,14 @@ static int __init imx_weim_gpr_setup(struct platform_device *pdev) } /* 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, reg_idx, num_regs; + struct cs_timing *cst; if (WARN_ON(devtype->cs_regs_count > MAX_CS_REGS_COUNT)) return -EINVAL;@@ -145,10 +158,23 @@ 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))) {
There should be space around *.
+ 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));Ditto. Shawn
quoted hunk ↗ jump to hunk
+ } } return 0;@@ -162,6 +188,7 @@ 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);@@ -170,7 +197,7 @@ 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);-- 2.17.1