clk: ux500: Implement the missing CLKOUT clocks

This implements the two missing CLKOUT clocks for the ux500
(well really U8500/DB8500) SoC.

The clocks are initialized using a specific parent and
divider and these are specified in the device tree, see
the separate binding patch.

The implementation is a bit different in that it will only
create the clock in the clock framework if a user appears
in the device tree, rather than it being registered upfront
like most of the other clocks. This is because the clock
needs parameters for source and divider from the consumer
phandle for the clock to be set up properly when the clock
is registered.

There could be more than one user of a CLKOUT clock, but
we have not seen this in practice. If this happens the
framework prints and info and returns the previously
registered clock.

Using the clocks requires also muxing the CLKOUT1 or
CLKOUT2 to the appropriate pad. In practice this is
achived in a pinctrl handle in the DTS node for the device
using the CLKOUT clock, so this muxing is done separately
from the clock itself. Example:

  haptic@49 {
    compatible = "immersion,isa1200";
    reg = <0x49>;
    (...)
    /* clkout1 from ACLK divided by 8 */
    clocks = <&clkout_clk DB8500_CLKOUT_1 DB8500_CLKOUT_SRC_ACLK 8>;
    pinctrl-names = "default";
    pinctrl-0 = <&isa1200_janice_default>;
  };

  isa1200_janice_default: isa1200_janice {
    /* Bring out clkout1 on pin GPIO227 pin AH7 */
    janice_mux {
      function = "clkout";
      groups = "clkout1_a_1";
    };
    janice_cfg1 {
      pins = "GPIO227_AH7";
      ste,config = <&out_lo>;
    };
  (...)

This was tested successfully with the Immersion ISA1200
haptic feedback unit on the Samsung Galaxy S Advance GT-I9070
(Janice) mobile phone.

As the CLKOUT clocks need some undefined fixed rate parent
clocks that are currently missing from the PRCMU clock
implementation, the three simplest are added in this patch:
clk38m_to_clkgen, aclk and sysclk. The only parent not yet
available in the implementation is clk009, which is a kind
of special muxed and divided clock which isn't even
implemented in the vendor clock driver.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220414221751.323525-6-linus.walleij@linaro.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/ux500/clk-prcmu.c

@@ -14,6 +14,7 @@
 #include "clk.h"
 
 #define to_clk_prcmu(_hw) container_of(_hw, struct clk_prcmu, hw)
+#define to_clk_prcmu_clkout(_hw) container_of(_hw, struct clk_prcmu_clkout, hw)
 
 struct clk_prcmu {
 	struct clk_hw hw;
@@ -21,6 +22,13 @@ struct clk_prcmu {
 	int opp_requested;
 };
 
+struct clk_prcmu_clkout {
+	struct clk_hw hw;
+	u8 clkout_id;
+	u8 source;
+	u8 divider;
+};
+
 /* PRCMU clock operations. */
 
 static int clk_prcmu_prepare(struct clk_hw *hw)
@@ -284,3 +292,109 @@ struct clk_hw *clk_reg_prcmu_opp_volt_scalable(const char *name,
 	return clk_reg_prcmu(name, parent_name, cg_sel, rate, flags,
 			&clk_prcmu_opp_volt_scalable_ops);
 }
+
+/* The clkout (external) clock is special and need special ops */
+
+static int clk_prcmu_clkout_prepare(struct clk_hw *hw)
+{
+	struct clk_prcmu_clkout *clk = to_clk_prcmu_clkout(hw);
+
+	return prcmu_config_clkout(clk->clkout_id, clk->source, clk->divider);
+}
+
+static void clk_prcmu_clkout_unprepare(struct clk_hw *hw)
+{
+	struct clk_prcmu_clkout *clk = to_clk_prcmu_clkout(hw);
+	int ret;
+
+	/* The clkout clock is disabled by dividing by 0 */
+	ret = prcmu_config_clkout(clk->clkout_id, clk->source, 0);
+	if (ret)
+		pr_err("clk_prcmu: %s failed to disable %s\n", __func__,
+		       clk_hw_get_name(hw));
+}
+
+static unsigned long clk_prcmu_clkout_recalc_rate(struct clk_hw *hw,
+						  unsigned long parent_rate)
+{
+	struct clk_prcmu_clkout *clk = to_clk_prcmu_clkout(hw);
+
+	return (parent_rate / clk->divider);
+}
+
+static u8 clk_prcmu_clkout_get_parent(struct clk_hw *hw)
+{
+	struct clk_prcmu_clkout *clk = to_clk_prcmu_clkout(hw);
+
+	return clk->source;
+}
+
+static int clk_prcmu_clkout_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_prcmu_clkout *clk = to_clk_prcmu_clkout(hw);
+
+	clk->source = index;
+	/* Make sure the change reaches the hardware immediately */
+	if (clk_hw_is_prepared(hw))
+		return clk_prcmu_clkout_prepare(hw);
+	return 0;
+}
+
+static const struct clk_ops clk_prcmu_clkout_ops = {
+	.prepare = clk_prcmu_clkout_prepare,
+	.unprepare = clk_prcmu_clkout_unprepare,
+	.recalc_rate = clk_prcmu_clkout_recalc_rate,
+	.get_parent = clk_prcmu_clkout_get_parent,
+	.set_parent = clk_prcmu_clkout_set_parent,
+};
+
+struct clk_hw *clk_reg_prcmu_clkout(const char *name,
+				    const char * const *parent_names,
+				    int num_parents,
+				    u8 source, u8 divider)
+
+{
+	struct clk_prcmu_clkout *clk;
+	struct clk_init_data clk_prcmu_clkout_init;
+	u8 clkout_id;
+	int ret;
+
+	if (!name) {
+		pr_err("clk_prcmu_clkout: %s invalid arguments passed\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (!strcmp(name, "clkout1"))
+		clkout_id = 0;
+	else if (!strcmp(name, "clkout2"))
+		clkout_id = 1;
+	else {
+		pr_err("clk_prcmu_clkout: %s bad clock name\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+
+	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
+	if (!clk)
+		return ERR_PTR(-ENOMEM);
+
+	clk->clkout_id = clkout_id;
+	clk->source = source;
+	clk->divider = divider;
+
+	clk_prcmu_clkout_init.name = name;
+	clk_prcmu_clkout_init.ops = &clk_prcmu_clkout_ops;
+	clk_prcmu_clkout_init.flags = CLK_GET_RATE_NOCACHE;
+	clk_prcmu_clkout_init.parent_names = parent_names;
+	clk_prcmu_clkout_init.num_parents = num_parents;
+	clk->hw.init = &clk_prcmu_clkout_init;
+
+	ret = clk_hw_register(NULL, &clk->hw);
+	if (ret)
+		goto free_clkout;
+
+	return &clk->hw;
+free_clkout:
+	kfree(clk);
+	pr_err("clk_prcmu_clkout: %s failed to register clk\n", __func__);
+	return ERR_PTR(-ENOMEM);
+}

drivers/clk/ux500/clk.h

@@ -60,6 +60,11 @@ struct clk_hw *clk_reg_prcmu_opp_volt_scalable(const char *name,
 					       unsigned long rate,
 					       unsigned long flags);
 
+struct clk_hw *clk_reg_prcmu_clkout(const char *name,
+				    const char * const *parent_names,
+				    int num_parents,
+				    u8 source, u8 divider);
+
 struct clk *clk_reg_sysctrl_gate(struct device *dev,
 				 const char *name,
 				 const char *parent_name,

drivers/clk/ux500/u8500_of_clk.c

@@ -17,6 +17,7 @@
 
 static struct clk *prcc_pclk[(PRCC_NUM_PERIPH_CLUSTERS + 1) * PRCC_PERIPHS_PER_CLUSTER];
 static struct clk *prcc_kclk[(PRCC_NUM_PERIPH_CLUSTERS + 1) * PRCC_PERIPHS_PER_CLUSTER];
+static struct clk_hw *clkout_clk[2];
 
 #define PRCC_SHOW(clk, base, bit) \
 	clk[(base * PRCC_PERIPHS_PER_CLUSTER) + bit]
@@ -56,6 +57,71 @@ static struct clk_hw_onecell_data u8500_prcmu_hw_clks = {
 	.num = PRCMU_NUM_CLKS,
 };
 
+/* Essentially names for the first PRCMU_CLKSRC_* defines */
+static const char * const u8500_clkout_parents[] = {
+	"clk38m_to_clkgen",
+	"aclk",
+	/* Just called "sysclk" in documentation */
+	"ab8500_sysclk",
+	"lcdclk",
+	"sdmmcclk",
+	"tvclk",
+	"timclk",
+	/* CLK009 is not implemented, add it if you need it */
+	"clk009",
+};
+
+static struct clk_hw *ux500_clkout_get(struct of_phandle_args *clkspec,
+				       void *data)
+{
+	u32 id, source, divider;
+	struct clk_hw *clkout;
+
+	if (clkspec->args_count != 3)
+		return  ERR_PTR(-EINVAL);
+
+	id = clkspec->args[0];
+	source = clkspec->args[1];
+	divider = clkspec->args[2];
+
+	if (id > 1) {
+		pr_err("%s: invalid clkout ID %d\n", __func__, id);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (clkout_clk[id]) {
+		pr_info("%s: clkout%d already registered, not reconfiguring\n",
+			__func__, id + 1);
+		return clkout_clk[id];
+	}
+
+	if (source > 7) {
+		pr_err("%s: invalid source ID %d\n", __func__, source);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (divider == 0 || divider > 63) {
+		pr_err("%s: invalid divider %d\n", __func__, divider);
+		return ERR_PTR(-EINVAL);
+	}
+
+	pr_debug("registering clkout%d with source %d and divider %d\n",
+		 id + 1, source, divider);
+
+	clkout = clk_reg_prcmu_clkout(id ? "clkout2" : "clkout1",
+				      u8500_clkout_parents,
+				      ARRAY_SIZE(u8500_clkout_parents),
+				      source, divider);
+	if (IS_ERR(clkout)) {
+		pr_err("failed to register clkout%d\n",  id + 1);
+		return ERR_CAST(clkout);
+	}
+
+	clkout_clk[id] = clkout;
+
+	return clkout;
+}
+
 static void u8500_clk_init(struct device_node *np)
 {
 	struct prcmu_fw_version *fw_version;
@@ -99,7 +165,17 @@ static void u8500_clk_init(struct device_node *np)
 		clk_reg_prcmu_gate("ddr_pll", NULL, PRCMU_PLLDDR,
 				   CLK_IGNORE_UNUSED);
 
-	/* FIXME: Add sys, ulp and int clocks here. */
+	/*
+	 * Read-only clocks that only return their current rate, only used
+	 * as parents to other clocks and not visible in the device tree.
+	 * clk38m_to_clkgen is the same as the SYSCLK, i.e. the root clock.
+	 */
+	clk_reg_prcmu_rate("clk38m_to_clkgen", NULL, PRCMU_SYSCLK,
+			   CLK_IGNORE_UNUSED);
+	clk_reg_prcmu_rate("aclk", NULL, PRCMU_ACLK,
+			   CLK_IGNORE_UNUSED);
+
+	/* TODO: add CLK009 if needed */
 
 	rtc_clk = clk_register_fixed_rate(NULL, "rtc32k", "NULL",
 				CLK_IGNORE_UNUSED,
@@ -223,12 +299,6 @@ static void u8500_clk_init(struct device_node *np)
 	twd_clk = clk_register_fixed_factor(NULL, "smp_twd", "armss",
 				CLK_IGNORE_UNUSED, 1, 2);
 
-	/*
-	 * FIXME: Add special handled PRCMU clocks here:
-	 * 1. clkout0yuv, use PRCMU as parent + need regulator + pinctrl.
-	 * 2. ab9540_clkout1yuv, see clkout0yuv
-	 */
-
 	/* PRCC P-clocks */
 	clk = clk_reg_prcc_pclk("p1_pclk0", "per1clk", bases[CLKRST1_INDEX],
 				BIT(0), 0);
@@ -526,6 +596,9 @@ static void u8500_clk_init(struct device_node *np)
 			of_clk_add_hw_provider(child, of_clk_hw_onecell_get,
 					       &u8500_prcmu_hw_clks);
 
+		if (of_node_name_eq(child, "clkout-clock"))
+			of_clk_add_hw_provider(child, ux500_clkout_get, NULL);
+
 		if (of_node_name_eq(child, "prcc-periph-clock"))
 			of_clk_add_provider(child, ux500_twocell_get, prcc_pclk);