On Thu, Dec 06, 2018 at 02:26:33PM -0500, Sven Van Asbroeck wrote:
> 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@xxxxxxxxxxxxxx>
> ---
> 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?
> #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
> + }
> }
>
> 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
>
