serial: uniphier: set clock rate without clock-frequency property

In Linux, the clock rate of the UART is given by the clock driver.

If you try to follow that in U-Boot, you would end up with adding
more u-boot,dm-pre-reloc properties, and also the clock driver would
be too big for SPL, which is used for UniPhier ARMv7 platform.

The current solution is to add 'clock-frequency' property to the
UART nodes, but it does not exist in the DT files in Linux.  I do
not want to let DT diverge for U-Boot.

Check the SoC compatible and set the clock rate according to it.
This will be helpful to sync DT between Linux and U-Boot.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

drivers/serial/serial_uniphier.c

@@ -7,6 +7,7 @@
 
 #include <common.h>
 #include <dm.h>
+#include <linux/bug.h>
 #include <linux/io.h>
 #include <linux/serial_reg.h>
 #include <linux/sizes.h>
@@ -87,11 +88,34 @@ static int uniphier_serial_pending(struct udevice *dev, bool input)
 		return !(readl(&port->lsr) & UART_LSR_THRE);
 }
 
+/*
+ * SPL does not have enough memory footprint for the clock driver.
+ * Hardcode clock frequency for each SoC.
+ */
+struct uniphier_serial_clk_data {
+	const char *compatible;
+	unsigned int clk_rate;
+};
+
+static const struct uniphier_serial_clk_data uniphier_serial_clk_data[] = {
+	{ .compatible = "socionext,uniphier-ld4",  .clk_rate = 36864000 },
+	{ .compatible = "socionext,uniphier-pro4", .clk_rate = 73728000 },
+	{ .compatible = "socionext,uniphier-sld8", .clk_rate = 80000000 },
+	{ .compatible = "socionext,uniphier-pro5", .clk_rate = 73728000 },
+	{ .compatible = "socionext,uniphier-pxs2", .clk_rate = 88888888 },
+	{ .compatible = "socionext,uniphier-ld6b", .clk_rate = 88888888 },
+	{ .compatible = "socionext,uniphier-ld11", .clk_rate = 58823529 },
+	{ .compatible = "socionext,uniphier-ld20", .clk_rate = 58823529 },
+	{ .compatible = "socionext,uniphier-pxs3", .clk_rate = 58823529 },
+	{ /* sentinel */ },
+};
+
 static int uniphier_serial_probe(struct udevice *dev)
 {
-	DECLARE_GLOBAL_DATA_PTR;
 	struct uniphier_serial_priv *priv = dev_get_priv(dev);
 	struct uniphier_serial __iomem *port;
+	const struct uniphier_serial_clk_data *clk_data;
+	ofnode root_node;
 	fdt_addr_t base;
 	u32 tmp;
 
@@ -105,8 +129,19 @@ static int uniphier_serial_probe(struct udevice *dev)
 
 	priv->membase = port;
 
-	priv->uartclk = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
-				       "clock-frequency", 0);
+	root_node = ofnode_path("/");
+	clk_data = uniphier_serial_clk_data;
+	while (clk_data->compatible) {
+		if (ofnode_device_is_compatible(root_node,
+						clk_data->compatible))
+			break;
+		clk_data++;
+	}
+
+	if (WARN_ON(!clk_data->compatible))
+		return -ENOTSUPP;
+
+	priv->uartclk = clk_data->clk_rate;
 
 	tmp = readl(&port->lcr_mcr);
 	tmp &= ~LCR_MASK;