Re: [RFC v2] ARM: memory: da8xx-ddrctl: new driver

Bartosz Golaszewski [off-list ref] writes:

Axel's series for the USB PHY reminded me that the PHY also has some
config registers in this same area, and his series creates a syscon for
a similar range of registers.

Could you create a syscon for the SYSCFG0 registers, which would then
be used by ths driver and your other drivers/bus driver?  Then the
binding  would just reference the sysconf via phandle, and your driver
can use syscon_regmap_lookup_by_phandle()

nit: call this shift instead, which will also map well onto the regmap
accessors (which you'll use when switching to syscon.)

+};
+
+static const struct da8xx_ddrctl_config_knob da8xx_ddrctl_knobs[] = {
+	{
+		.name = "da850-pbbpr",
+		.reg = 0x20,
+		.mask = 0xffffff00,
+		.offset = 0,
+	},
+};
+
+struct da8xx_ddrctl_setting {
+	const char *name;
+	u32 val;
+};
+
+struct da8xx_ddrctl_board_settings {
+	const char *board;
+	const struct da8xx_ddrctl_setting *settings;
+};
+
+static const struct da8xx_ddrctl_setting da850_lcdk_ddrctl_settings[] = {
+	{
+		.name = "da850-pbbpr",
+		.val = 0x20,
+	},
+	{ }
+};
+
+static const struct da8xx_ddrctl_board_settings da8xx_ddrctl_board_confs[] = {
+	{
+		.board = "ti,da850-lcdk",
+		.settings = da850_lcdk_ddrctl_settings,
+	},
+};
+
+static const struct da8xx_ddrctl_config_knob *
+da8xx_ddrctl_match_knob(const struct da8xx_ddrctl_setting *setting)
+{
+	const struct da8xx_ddrctl_config_knob *knob;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_knobs); i++) {
+		knob = &da8xx_ddrctl_knobs[i];
+
+		if (strcmp(knob->name, setting->name) == 0)
+			return knob;
+	}
+
+	return NULL;
+}
+
+static const struct da8xx_ddrctl_setting *da8xx_ddrctl_get_board_settings(void)
+{
+	const struct da8xx_ddrctl_board_settings *board_settings;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_board_confs); i++) {
+		board_settings = &da8xx_ddrctl_board_confs[0];

Looks like that '0' should be 'i' ?

+		if (of_machine_is_compatible(board_settings->board))
+			return board_settings->settings;
+	}
+
+	return NULL;
+}
+
+static int da8xx_ddrctl_probe(struct platform_device *pdev)
+{
+	const struct da8xx_ddrctl_config_knob *knob;
+	const struct da8xx_ddrctl_setting *setting;
+	struct device_node *node;
+	struct resource *res;
+	void __iomem *ddrctl;
+	struct device *dev;
+	u32 reg;
+
+	dev = &pdev->dev;
+	node = dev->of_node;
+
+	setting = da8xx_ddrctl_get_board_settings();
+	if (!setting) {
+		dev_err(dev, "no settings for board '%s'\n",
+			of_flat_dt_get_machine_name());
+		return -EINVAL;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ddrctl = devm_ioremap_resource(dev, res);
+	if (IS_ERR(ddrctl)) {
+		dev_err(dev, "unable to map memory controller registers\n");
+		return PTR_ERR(ddrctl);
+	}
+
+	for (; setting->name; setting++) {
+		knob = da8xx_ddrctl_match_knob(setting);
+		if (!knob) {
+			dev_warn(dev,
+				 "no such config option: %s\n", setting->name);
+			continue;
+		}
+
+		if (knob->reg > (res->end - res->start - sizeof(u32))) {
+			dev_warn(dev,
+				 "register offset of '%s' exceeds mapped memory size\n",
+				 knob->name);
+			continue;
+		}
+
+		reg = __raw_readl(ddrctl + knob->reg);
+		reg &= knob->mask;
+		reg |= setting->val << knob->offset;
+
+		dev_dbg(dev, "writing 0x%08x to %s\n", reg, setting->name);
+
+		__raw_writel(reg, ddrctl + knob->reg);

nit: I don't think you need the __raw accessors here.

But in any case, moving to syscon you'll be using regmap accessors, and
this can just be converted to a single regmap_update_bits.

Kevin

+	}
+
+	return 0;
+}
+
+static const struct of_device_id da8xx_ddrctl_of_match[] = {
+	{ .compatible = "ti,da850-ddr-controller", },
+	{ },
+};
+
+static struct platform_driver da8xx_ddrctl_driver = {
+	.probe = da8xx_ddrctl_probe,
+	.driver = {
+		.name = "da850-ddr-controller",
+		.of_match_table = da8xx_ddrctl_of_match,
+	},
+};
+module_platform_driver(da8xx_ddrctl_driver);
+
+MODULE_AUTHOR("Bartosz Golaszewski [off-list ref]");
+MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");
+MODULE_LICENSE("GPL v2");

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