[PATCH 6/6] memory: ti-aemif-cs: Compute timing configuration from DT parsing

[Bastien Curutchet]

The Linux bindings of the AEMIF offer properties that specify the
transaction timings for each chips select.

Add parsing of these properties to calculate the chip select's
configuration from them and the rate of the AEMIF's reference clock.

Signed-off-by: Bastien Curutchet <bastien.curutchet at bootlin.com>
---
 drivers/memory/ti-aemif-cs.c | 122 +++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

diff --git a/drivers/memory/ti-aemif-cs.c b/drivers/memory/ti-aemif-cs.c
index 80166e3e6a..0fcfee6f0b 100644
--- a/drivers/memory/ti-aemif-cs.c
+++ b/drivers/memory/ti-aemif-cs.c
@@ -5,6 +5,7 @@
  */
 #include <asm/io.h>
 #include <clk.h>
+#include <div64.h>
 #include <dm.h>
 #include "ti-aemif-cs.h"
 
@@ -21,6 +22,20 @@
 #define AEMIF_CFG_TURN_AROUND(v)	(((v) & 0x03) << 2)
 #define AEMIF_CFG_WIDTH(v)		(((v) & 0x03) << 0)
 
+#define SSTROBE_EN			0x1
+#define EW_EN				0x1
+
+#define WSETUP_MAX			0xf
+#define WSTROBE_MAX			0x3f
+#define WHOLD_MAX			0x7
+#define RSETUP_MAX			0xf
+#define RSTROBE_MAX			0x3f
+#define RHOLD_MAX			0x7
+#define TA_MAX				0x3
+
+#define WIDTH_8BITS			0x0
+#define WIDTH_16BITS			0x1
+
 #define set_config_field(reg, field, val)				\
 	do {								\
 		if ((val) != -1) {					\
@@ -49,6 +64,111 @@ void aemif_cs_configure(int cs, struct aemif_config *cfg)
 	__raw_writel(tmp, cfg->base + AEMIF_CONFIG(cs));
 }
 
+struct ti_aemif_cs {
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static unsigned int aemif_calc_cfg(ulong rate, u64 timing_ns, u32 max_cfg)
+{
+	u64 result;
+
+	if (!timing_ns)
+		return 0;
+
+	result = DIV_ROUND_UP_ULL(timing_ns * rate, 1000000000ULL);
+
+	if (result - 1 > max_cfg)
+		return max_cfg;
+
+	return result - 1;
+}
+
+static int aemif_cs_set_timings(struct udevice *dev)
+{
+	struct ti_aemif_cs *priv = dev_get_priv(dev);
+	ulong rate = clk_get_rate(priv->clk);
+	struct aemif_config cfg = {};
+	u32 val;
+	u32 cs;
+
+	if (dev_read_u32(dev, "ti,cs-chipselect", &cs))
+		return -EINVAL;
+
+/*
+ * On DaVinci SoCs, chipselect is in range [2-5]
+ * On Keystone SoCs, chipselect is in range [0-3]
+ * The logic to access the configuration registers expects the CS to be in the
+ * Keystone range so a -2 offset is applied on DaVinci SoCs
+ */
+	if (IS_ENABLED(CONFIG_ARCH_DAVINCI)) {
+		if (cs < 2 || cs > 5)
+			return -EINVAL;
+		cs -= 2;
+	} else if (IS_ENABLED(CONFIG_ARCH_KEYSTONE)) {
+		if (cs > 3)
+			return -EINVAL;
+	}
+
+	if (dev_read_bool(dev, "ti,cs-select-strobe-mode"))
+		cfg.select_strobe = SSTROBE_EN;
+
+	if (dev_read_bool(dev, "ti,cs-extended-wait-mode"))
+		cfg.extend_wait = EW_EN;
+
+	val = dev_read_u32_default(dev, "ti,cs-write-setup-ns", U32_MAX);
+	cfg.wr_setup = aemif_calc_cfg(rate, val, WSETUP_MAX);
+
+	val = dev_read_u32_default(dev, "ti,cs-write-strobe-ns", U32_MAX);
+	cfg.wr_strobe = aemif_calc_cfg(rate, val, WSTROBE_MAX);
+
+	val = dev_read_u32_default(dev, "ti,cs-write-hold-ns", U32_MAX);
+	cfg.wr_hold = aemif_calc_cfg(rate, val, WHOLD_MAX);
+
+	val = dev_read_u32_default(dev, "ti,cs-read-setup-ns", U32_MAX);
+	cfg.rd_setup = aemif_calc_cfg(rate, val, RSETUP_MAX);
+
+	val = dev_read_u32_default(dev, "ti,cs-read-strobe-ns", U32_MAX);
+	cfg.rd_strobe = aemif_calc_cfg(rate, val, RSTROBE_MAX);
+
+	val = dev_read_u32_default(dev, "ti,cs-read-hold-ns", U32_MAX);
+	cfg.rd_hold = aemif_calc_cfg(rate, val, RHOLD_MAX);
+
+	val = dev_read_u32_default(dev, "ti,cs-min-turnaround-ns", U32_MAX);
+	cfg.turn_around = aemif_calc_cfg(rate, val, TA_MAX);
+
+	val = dev_read_u32_default(dev, "ti,cs-bus-width", 8);
+	if (val == 16)
+		cfg.width = WIDTH_16BITS;
+	else
+		cfg.width = WIDTH_8BITS;
+
+	cfg.base = priv->base;
+	aemif_cs_configure(cs, &cfg);
+
+	return 0;
+}
+
+static int aemif_cs_probe(struct udevice *dev)
+{
+	struct ti_aemif_cs *priv = dev_get_priv(dev);
+	struct udevice *aemif;
+
+	aemif = dev_get_parent(dev);
+	if (!aemif)
+		return -ENODEV;
+
+	priv->base = dev_read_addr_ptr(aemif);
+	if (!priv->base)
+		return -EINVAL;
+
+	priv->clk = devm_clk_get(aemif, "aemif");
+	if (IS_ERR(priv->clk))
+		return -EINVAL;
+
+	return aemif_cs_set_timings(dev);
+}
+
 static const struct udevice_id aemif_cs_ids[] = {
 	{ .compatible = "ti,da850-aemif-cs", },
 	{},
@@ -58,4 +178,6 @@ U_BOOT_DRIVER(ti_aemif_cs) = {
 	.name = "ti_aemif_cs",
 	.id = UCLASS_MEMORY,
 	.of_match = aemif_cs_ids,
+	.probe = aemif_cs_probe,
+	.priv_auto = sizeof(struct ti_aemif_cs),
 };
-- 
2.47.0