bus: ti-sysc: Add quirk handling for external optional functional clock

We cannot access mcpdm registers at all unless there is an optional pdmclk
configured. As this is currently only needed for mcpdm, let's check for
mcpdm in sysc_get_clocks(). If it turns out to be needed for other modules
too, we can add more flags to the quirks table for this.
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/bus/ti-sysc.c

@@ -47,7 +47,10 @@ enum sysc_clocks {
 	SYSC_MAX_CLOCKS,
 };
 
-static const char * const clock_names[SYSC_ICK + 1] = { "fck", "ick", };
+static const char * const clock_names[SYSC_MAX_CLOCKS] = {
+	"fck", "ick", "opt0", "opt1", "opt2", "opt3", "opt4",
+	"opt5", "opt6", "opt7",
+};
 
 #define SYSC_IDLEMODE_MASK		3
 #define SYSC_CLOCKACTIVITY_MASK		3
@@ -129,6 +132,81 @@ static u32 sysc_read_revision(struct sysc *ddata)
 	return sysc_read(ddata, offset);
 }
 
+static int sysc_add_named_clock_from_child(struct sysc *ddata,
+					   const char *name,
+					   const char *optfck_name)
+{
+	struct device_node *np = ddata->dev->of_node;
+	struct device_node *child;
+	struct clk_lookup *cl;
+	struct clk *clock;
+	const char *n;
+
+	if (name)
+		n = name;
+	else
+		n = optfck_name;
+
+	/* Does the clock alias already exist? */
+	clock = of_clk_get_by_name(np, n);
+	if (!IS_ERR(clock)) {
+		clk_put(clock);
+
+		return 0;
+	}
+
+	child = of_get_next_available_child(np, NULL);
+	if (!child)
+		return -ENODEV;
+
+	clock = devm_get_clk_from_child(ddata->dev, child, name);
+	if (IS_ERR(clock))
+		return PTR_ERR(clock);
+
+	/*
+	 * Use clkdev_add() instead of clkdev_alloc() to avoid the MAX_DEV_ID
+	 * limit for clk_get(). If cl ever needs to be freed, it should be done
+	 * with clkdev_drop().
+	 */
+	cl = kcalloc(1, sizeof(*cl), GFP_KERNEL);
+	if (!cl)
+		return -ENOMEM;
+
+	cl->con_id = n;
+	cl->dev_id = dev_name(ddata->dev);
+	cl->clk = clock;
+	clkdev_add(cl);
+
+	clk_put(clock);
+
+	return 0;
+}
+
+static int sysc_init_ext_opt_clock(struct sysc *ddata, const char *name)
+{
+	const char *optfck_name;
+	int error, index;
+
+	if (ddata->nr_clocks < SYSC_OPTFCK0)
+		index = SYSC_OPTFCK0;
+	else
+		index = ddata->nr_clocks;
+
+	if (name)
+		optfck_name = name;
+	else
+		optfck_name = clock_names[index];
+
+	error = sysc_add_named_clock_from_child(ddata, name, optfck_name);
+	if (error)
+		return error;
+
+	ddata->clock_roles[index] = optfck_name;
+	ddata->nr_clocks++;
+
+	return 0;
+}
+
 static int sysc_get_one_clock(struct sysc *ddata, const char *name)
 {
 	int error, i, index = -ENODEV;
@@ -200,6 +278,12 @@ static int sysc_get_clocks(struct sysc *ddata)
 	if (ddata->nr_clocks < 1)
 		return 0;
 
+	if ((ddata->cfg.quirks & SYSC_QUIRK_EXT_OPT_CLOCK)) {
+		error = sysc_init_ext_opt_clock(ddata, NULL);
+		if (error)
+			return error;
+	}
+
 	if (ddata->nr_clocks > SYSC_MAX_CLOCKS) {
 		dev_err(ddata->dev, "too many clocks for %pOF\n", np);
 
@@ -901,6 +985,11 @@ static const struct sysc_revision_quirk sysc_revision_quirks[] = {
 	SYSC_QUIRK("uart", 0, 0x50, 0x54, 0x58, 0x47422e03, 0xffffffff,
 		   SYSC_QUIRK_LEGACY_IDLE),
 
+	/* Quirks that need to be set based on the module address */
+	SYSC_QUIRK("mcpdm", 0x40132000, 0, 0x10, -1, 0x50000800, 0xffffffff,
+		   SYSC_QUIRK_EXT_OPT_CLOCK | SYSC_QUIRK_NO_RESET_ON_INIT |
+		   SYSC_QUIRK_SWSUP_SIDLE),
+
 #ifdef DEBUG
 	SYSC_QUIRK("adc", 0, 0, 0x10, -1, 0x47300001, 0xffffffff, 0),
 	SYSC_QUIRK("atl", 0, 0, -1, -1, 0x0a070100, 0xffffffff, 0),

include/linux/platform_data/ti-sysc.h

@@ -46,6 +46,7 @@ struct sysc_regbits {
 	s8 emufree_shift;
 };
 
+#define SYSC_QUIRK_EXT_OPT_CLOCK	BIT(10)
 #define SYSC_QUIRK_LEGACY_IDLE		BIT(9)
 #define SYSC_QUIRK_RESET_STATUS		BIT(8)
 #define SYSC_QUIRK_NO_IDLE		BIT(7)