clk: at91: clk-master: add master clock support for SAMA7G5

Add master clock support (MCK1..4) for SAMA7G5. SAMA7G5's PMC has
multiple master clocks feeding different subsystems. One of them
feeds image subsystem and is changeable based on image subsystem
needs.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/1595403506-8209-13-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/at91/clk-master.c

@@ -17,30 +17,49 @@
 #define MASTER_DIV_SHIFT	8
 #define MASTER_DIV_MASK		0x3
 
+#define PMC_MCR			0x30
+#define PMC_MCR_ID_MSK		GENMASK(3, 0)
+#define PMC_MCR_CMD		BIT(7)
+#define PMC_MCR_DIV		GENMASK(10, 8)
+#define PMC_MCR_CSS		GENMASK(20, 16)
+#define PMC_MCR_CSS_SHIFT	(16)
+#define PMC_MCR_EN		BIT(28)
+
+#define PMC_MCR_ID(x)		((x) & PMC_MCR_ID_MSK)
+
+#define MASTER_MAX_ID		4
+
 #define to_clk_master(hw) container_of(hw, struct clk_master, hw)
 
 struct clk_master {
 	struct clk_hw hw;
 	struct regmap *regmap;
+	spinlock_t *lock;
 	const struct clk_master_layout *layout;
 	const struct clk_master_characteristics *characteristics;
+	u32 *mux_table;
 	u32 mckr;
+	int chg_pid;
+	u8 id;
+	u8 parent;
+	u8 div;
 };
 
-static inline bool clk_master_ready(struct regmap *regmap)
+static inline bool clk_master_ready(struct clk_master *master)
 {
+	unsigned int bit = master->id ? AT91_PMC_MCKXRDY : AT91_PMC_MCKRDY;
 	unsigned int status;
 
-	regmap_read(regmap, AT91_PMC_SR, &status);
+	regmap_read(master->regmap, AT91_PMC_SR, &status);
 
-	return !!(status & AT91_PMC_MCKRDY);
+	return !!(status & bit);
 }
 
 static int clk_master_prepare(struct clk_hw *hw)
 {
 	struct clk_master *master = to_clk_master(hw);
 
-	while (!clk_master_ready(master->regmap))
+	while (!clk_master_ready(master))
 		cpu_relax();
 
 	return 0;
@@ -50,7 +69,7 @@ static int clk_master_is_prepared(struct clk_hw *hw)
 {
 	struct clk_master *master = to_clk_master(hw);
 
-	return clk_master_ready(master->regmap);
+	return clk_master_ready(master);
 }
 
 static unsigned long clk_master_recalc_rate(struct clk_hw *hw,
@@ -143,6 +162,287 @@ at91_clk_register_master(struct regmap *regmap,
 	return hw;
 }
 
+static unsigned long
+clk_sama7g5_master_recalc_rate(struct clk_hw *hw,
+			       unsigned long parent_rate)
+{
+	struct clk_master *master = to_clk_master(hw);
+
+	return DIV_ROUND_CLOSEST_ULL(parent_rate, (1 << master->div));
+}
+
+static void clk_sama7g5_master_best_diff(struct clk_rate_request *req,
+					 struct clk_hw *parent,
+					 unsigned long parent_rate,
+					 long *best_rate,
+					 long *best_diff,
+					 u32 div)
+{
+	unsigned long tmp_rate, tmp_diff;
+
+	if (div == MASTER_PRES_MAX)
+		tmp_rate = parent_rate / 3;
+	else
+		tmp_rate = parent_rate >> div;
+
+	tmp_diff = abs(req->rate - tmp_rate);
+
+	if (*best_diff < 0 || *best_diff >= tmp_diff) {
+		*best_rate = tmp_rate;
+		*best_diff = tmp_diff;
+		req->best_parent_rate = parent_rate;
+		req->best_parent_hw = parent;
+	}
+}
+
+static int clk_sama7g5_master_determine_rate(struct clk_hw *hw,
+					     struct clk_rate_request *req)
+{
+	struct clk_master *master = to_clk_master(hw);
+	struct clk_rate_request req_parent = *req;
+	struct clk_hw *parent;
+	long best_rate = LONG_MIN, best_diff = LONG_MIN;
+	unsigned long parent_rate;
+	unsigned int div, i;
+
+	/* First: check the dividers of MCR. */
+	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
+		parent = clk_hw_get_parent_by_index(hw, i);
+		if (!parent)
+			continue;
+
+		parent_rate = clk_hw_get_rate(parent);
+		if (!parent_rate)
+			continue;
+
+		for (div = 0; div < MASTER_PRES_MAX + 1; div++) {
+			clk_sama7g5_master_best_diff(req, parent, parent_rate,
+						     &best_rate, &best_diff,
+						     div);
+			if (!best_diff)
+				break;
+		}
+
+		if (!best_diff)
+			break;
+	}
+
+	/* Second: try to request rate form changeable parent. */
+	if (master->chg_pid < 0)
+		goto end;
+
+	parent = clk_hw_get_parent_by_index(hw, master->chg_pid);
+	if (!parent)
+		goto end;
+
+	for (div = 0; div < MASTER_PRES_MAX + 1; div++) {
+		if (div == MASTER_PRES_MAX)
+			req_parent.rate = req->rate * 3;
+		else
+			req_parent.rate = req->rate << div;
+
+		if (__clk_determine_rate(parent, &req_parent))
+			continue;
+
+		clk_sama7g5_master_best_diff(req, parent, req_parent.rate,
+					     &best_rate, &best_diff, div);
+
+		if (!best_diff)
+			break;
+	}
+
+end:
+	pr_debug("MCK: %s, best_rate = %ld, parent clk: %s @ %ld\n",
+		 __func__, best_rate,
+		 __clk_get_name((req->best_parent_hw)->clk),
+		req->best_parent_rate);
+
+	if (best_rate < 0)
+		return -EINVAL;
+
+	req->rate = best_rate;
+
+	return 0;
+}
+
+static u8 clk_sama7g5_master_get_parent(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long flags;
+	u8 index;
+
+	spin_lock_irqsave(master->lock, flags);
+	index = clk_mux_val_to_index(&master->hw, master->mux_table, 0,
+				     master->parent);
+	spin_unlock_irqrestore(master->lock, flags);
+
+	return index;
+}
+
+static int clk_sama7g5_master_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long flags;
+
+	if (index >= clk_hw_get_num_parents(hw))
+		return -EINVAL;
+
+	spin_lock_irqsave(master->lock, flags);
+	master->parent = clk_mux_index_to_val(master->mux_table, 0, index);
+	spin_unlock_irqrestore(master->lock, flags);
+
+	return 0;
+}
+
+static int clk_sama7g5_master_enable(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long flags;
+	unsigned int val, cparent;
+
+	spin_lock_irqsave(master->lock, flags);
+
+	regmap_write(master->regmap, PMC_MCR, PMC_MCR_ID(master->id));
+	regmap_read(master->regmap, PMC_MCR, &val);
+	regmap_update_bits(master->regmap, PMC_MCR,
+			   PMC_MCR_EN | PMC_MCR_CSS | PMC_MCR_DIV |
+			   PMC_MCR_CMD | PMC_MCR_ID_MSK,
+			   PMC_MCR_EN | (master->parent << PMC_MCR_CSS_SHIFT) |
+			   (master->div << MASTER_DIV_SHIFT) |
+			   PMC_MCR_CMD | PMC_MCR_ID(master->id));
+
+	cparent = (val & PMC_MCR_CSS) >> PMC_MCR_CSS_SHIFT;
+
+	/* Wait here only if parent is being changed. */
+	while ((cparent != master->parent) && !clk_master_ready(master))
+		cpu_relax();
+
+	spin_unlock_irqrestore(master->lock, flags);
+
+	return 0;
+}
+
+static void clk_sama7g5_master_disable(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(master->lock, flags);
+
+	regmap_write(master->regmap, PMC_MCR, master->id);
+	regmap_update_bits(master->regmap, PMC_MCR,
+			   PMC_MCR_EN | PMC_MCR_CMD | PMC_MCR_ID_MSK,
+			   PMC_MCR_CMD | PMC_MCR_ID(master->id));
+
+	spin_unlock_irqrestore(master->lock, flags);
+}
+
+static int clk_sama7g5_master_is_enabled(struct clk_hw *hw)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long flags;
+	unsigned int val;
+
+	spin_lock_irqsave(master->lock, flags);
+
+	regmap_write(master->regmap, PMC_MCR, master->id);
+	regmap_read(master->regmap, PMC_MCR, &val);
+
+	spin_unlock_irqrestore(master->lock, flags);
+
+	return !!(val & PMC_MCR_EN);
+}
+
+static int clk_sama7g5_master_set_rate(struct clk_hw *hw, unsigned long rate,
+				       unsigned long parent_rate)
+{
+	struct clk_master *master = to_clk_master(hw);
+	unsigned long div, flags;
+
+	div = DIV_ROUND_CLOSEST(parent_rate, rate);
+	if ((div > (1 << (MASTER_PRES_MAX - 1))) || (div & (div - 1)))
+		return -EINVAL;
+
+	if (div == 3)
+		div = MASTER_PRES_MAX;
+	else
+		div = ffs(div) - 1;
+
+	spin_lock_irqsave(master->lock, flags);
+	master->div = div;
+	spin_unlock_irqrestore(master->lock, flags);
+
+	return 0;
+}
+
+static const struct clk_ops sama7g5_master_ops = {
+	.enable = clk_sama7g5_master_enable,
+	.disable = clk_sama7g5_master_disable,
+	.is_enabled = clk_sama7g5_master_is_enabled,
+	.recalc_rate = clk_sama7g5_master_recalc_rate,
+	.determine_rate = clk_sama7g5_master_determine_rate,
+	.set_rate = clk_sama7g5_master_set_rate,
+	.get_parent = clk_sama7g5_master_get_parent,
+	.set_parent = clk_sama7g5_master_set_parent,
+};
+
+struct clk_hw * __init
+at91_clk_sama7g5_register_master(struct regmap *regmap,
+				 const char *name, int num_parents,
+				 const char **parent_names,
+				 u32 *mux_table,
+				 spinlock_t *lock, u8 id,
+				 bool critical, int chg_pid)
+{
+	struct clk_master *master;
+	struct clk_hw *hw;
+	struct clk_init_data init;
+	unsigned long flags;
+	unsigned int val;
+	int ret;
+
+	if (!name || !num_parents || !parent_names || !mux_table ||
+	    !lock || id > MASTER_MAX_ID)
+		return ERR_PTR(-EINVAL);
+
+	master = kzalloc(sizeof(*master), GFP_KERNEL);
+	if (!master)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &sama7g5_master_ops;
+	init.parent_names = parent_names;
+	init.num_parents = num_parents;
+	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
+	if (chg_pid >= 0)
+		init.flags |= CLK_SET_RATE_PARENT;
+	if (critical)
+		init.flags |= CLK_IS_CRITICAL;
+
+	master->hw.init = &init;
+	master->regmap = regmap;
+	master->id = id;
+	master->chg_pid = chg_pid;
+	master->lock = lock;
+	master->mux_table = mux_table;
+
+	spin_lock_irqsave(master->lock, flags);
+	regmap_write(master->regmap, PMC_MCR, master->id);
+	regmap_read(master->regmap, PMC_MCR, &val);
+	master->parent = (val & PMC_MCR_CSS) >> PMC_MCR_CSS_SHIFT;
+	master->div = (val & PMC_MCR_DIV) >> MASTER_DIV_SHIFT;
+	spin_unlock_irqrestore(master->lock, flags);
+
+	hw = &master->hw;
+	ret = clk_hw_register(NULL, &master->hw);
+	if (ret) {
+		kfree(master);
+		hw = ERR_PTR(ret);
+	}
+
+	return hw;
+}
+
 const struct clk_master_layout at91rm9200_master_layout = {
 	.mask = 0x31F,
 	.pres_shift = 2,

drivers/clk/at91/pmc.h

@@ -154,6 +154,13 @@ at91_clk_register_master(struct regmap *regmap, const char *name,
 			 const struct clk_master_layout *layout,
 			 const struct clk_master_characteristics *characteristics);
 
+struct clk_hw * __init
+at91_clk_sama7g5_register_master(struct regmap *regmap,
+				 const char *name, int num_parents,
+				 const char **parent_names, u32 *mux_table,
+				 spinlock_t *lock, u8 id, bool critical,
+				 int chg_pid);
+
 struct clk_hw * __init
 at91_clk_register_peripheral(struct regmap *regmap, const char *name,
 			     const char *parent_name, u32 id);

include/linux/clk/at91_pmc.h

@@ -174,6 +174,7 @@
 #define		AT91_PMC_MOSCRCS	(1 << 17)		/* Main On-Chip RC [some SAM9] */
 #define		AT91_PMC_CFDEV		(1 << 18)		/* Clock Failure Detector Event [some SAM9] */
 #define		AT91_PMC_GCKRDY		(1 << 24)		/* Generated Clocks */
+#define		AT91_PMC_MCKXRDY	(1 << 26)		/* Master Clock x [x=1..4] Ready Status */
 #define	AT91_PMC_IMR		0x6c			/* Interrupt Mask Register */
 
 #define AT91_PMC_FSMR		0x70		/* Fast Startup Mode Register */