[U-Boot] [PATCH v3] DW SPI: Get clock value from Device Tree

[Eugeniy Paltsev]

Add option to set spi controller clock frequency via device tree
using standard clock bindings.
Old way of setting spi controller clock frequency (via implementation
of 'cm_get_spi_controller_clk_hz' function in platform specific code)
remains supported for backward compatibility with targets which don't use
generic clock framework.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev at synopsys.com>
---

Marek, Jagan,
How about this implementation?

As both SOCFPGA_GEN5 and SOCFPGA_ARRIA10 don't use generic clock framework,
we can determine way of clock getting based on CONFIG_IS_ENABLED(CLK) macro.

So we don't need any weak functions / soc-specific ifdefs in driver / changes
in SOCFPGA_* stuff.


Changes v2->v3:
  * get rid of soc-specific ifdefs in driver.

Changes v1->v2:
  * disable clock if we can't get the rate.
  * get rid of cm_get_spi_controller_clk_hz weak declaration.

 drivers/spi/designware_spi.c | 69 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
index 5aa507b..ad64949 100644
--- a/drivers/spi/designware_spi.c
+++ b/drivers/spi/designware_spi.c
@@ -11,6 +11,7 @@
  */
 
 #include <common.h>
+#include <clk.h>
 #include <dm.h>
 #include <errno.h>
 #include <malloc.h>
@@ -18,7 +19,13 @@
 #include <fdtdec.h>
 #include <linux/compat.h>
 #include <asm/io.h>
+/*
+ * Some targets (like SOCFPGA_GEN5 and SOCFPGA_ARRIA10) which don't implement
+ * generic clock framework and uses their clock_manager functions.
+ */
+#if !CONFIG_IS_ENABLED(OF_CONTROL) || !CONFIG_IS_ENABLED(CLK)
 #include <asm/arch/clock_manager.h>
+#endif
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -94,6 +101,7 @@ struct dw_spi_priv {
 	void __iomem *regs;
 	unsigned int freq;		/* Default frequency */
 	unsigned int mode;
+	unsigned long bus_clk_rate;
 
 	int bits_per_word;
 	u8 cs;			/* chip select pin */
@@ -176,14 +184,73 @@ static void spi_hw_init(struct dw_spi_priv *priv)
 	debug("%s: fifo_len=%d\n", __func__, priv->fifo_len);
 }
 
+#if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
+static int dw_spi_of_get_clk(struct udevice *bus)
+{
+	struct dw_spi_priv *priv = dev_get_priv(bus);
+	struct clk clk;
+	int ret;
+
+	ret = clk_get_by_index(bus, 0, &clk);
+	if (ret)
+		return -EINVAL;
+
+	ret = clk_enable(&clk);
+	if (ret && ret != -ENOSYS)
+		return ret;
+
+	priv->bus_clk_rate = clk_get_rate(&clk);
+	if (!priv->bus_clk_rate) {
+		clk_disable(&clk);
+		return -EINVAL;
+	}
+
+	clk_free(&clk);
+
+	return 0;
+}
+#endif
+
+static int dw_spi_get_clk(struct udevice *bus)
+{
+	struct dw_spi_priv *priv = dev_get_priv(bus);
+
+#if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
+	int ret;
+
+	/* Try to get clock frequency from device tree */
+	ret = dw_spi_of_get_clk(bus);
+	if (ret)
+		return ret;
+#else
+	/*
+	 * Some targets (like SOCFPGA_GEN5 and SOCFPGA_ARRIA10) don't implement
+	 * generic clock framework and use cm_get_spi_controller_clk_hz
+	 * function (defined in asm/arch/clock_manager.h) to get spi controller
+	 * clock frequency.
+	 */
+	priv->bus_clk_rate = cm_get_spi_controller_clk_hz();
+#endif
+
+	if (!priv->bus_clk_rate)
+		return -EINVAL;
+
+	return 0;
+}
+
 static int dw_spi_probe(struct udevice *bus)
 {
 	struct dw_spi_platdata *plat = dev_get_platdata(bus);
 	struct dw_spi_priv *priv = dev_get_priv(bus);
+	int ret;
 
 	priv->regs = plat->regs;
 	priv->freq = plat->frequency;
 
+	ret = dw_spi_get_clk(bus);
+	if (ret)
+		return ret;
+
 	/* Currently only bits_per_word == 8 supported */
 	priv->bits_per_word = 8;
 
@@ -369,7 +436,7 @@ static int dw_spi_set_speed(struct udevice *bus, uint speed)
 	spi_enable_chip(priv, 0);
 
 	/* clk_div doesn't support odd number */
-	clk_div = cm_get_spi_controller_clk_hz() / speed;
+	clk_div = priv->bus_clk_rate / speed;
 	clk_div = (clk_div + 1) & 0xfffe;
 	dw_writel(priv, DW_SPI_BAUDR, clk_div);
 
-- 
2.9.3