From: Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>
This patch adds Z clock divider support for R-Car Gen3 SoC.
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>
Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
---
v2 [Simon Horman]
* Use DIV_ROUND_CLOSEST_ULL instead of open-coding the same behaviour
using div_u64()
* Do not round rate to 100MHz in cpg_z_clk_recalc_rate
* Remove calculation for PLL post-divider, this is bogus.
Instead do not round to closest in cpg_z_clk_round_rate()
* Drop check for !prate in cpg_z_clk_round_rate
v1 [Simon Horman]
* Divide parent clock by 2 to give correct rate
* Use GENMASK, FIELD_{GET,PREP}
* Correct whitespace
* Arrange local variables in reverse Christmas tree order
v0 [Takeshi Kihara]
---
drivers/clk/renesas/rcar-gen3-cpg.c | 128 ++++++++++++++++++++++++++++++++++++
drivers/clk/renesas/rcar-gen3-cpg.h | 1 +
2 files changed, 129 insertions(+)
diff --git a/drivers/clk/renesas/rcar-gen3-cpg.c b/drivers/clk/renesas/rcar-gen3-cpg.c
index 951105816547..d98272a6075f 100644
--- a/drivers/clk/renesas/rcar-gen3-cpg.c
+++ b/drivers/clk/renesas/rcar-gen3-cpg.c
@@ -13,6 +13,7 @@
*/
#include <linux/bug.h>
+#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/device.h>
@@ -29,6 +30,129 @@
#define CPG_PLL2CR 0x002c
#define CPG_PLL4CR 0x01f4
+/*
+ * Z Clock
+ *
+ * Traits of this clock:
+ * prepare - clk_prepare only ensures that parents are prepared
+ * enable - clk_enable only ensures that parents are enabled
+ * rate - rate is adjustable. clk->rate = (parent->rate * mult / 32 ) / 2
+ * parent - fixed parent. No clk_set_parent support
+ */
+#define CPG_FRQCRB 0x00000004
+#define CPG_FRQCRB_KICK BIT(31)
+#define CPG_FRQCRC 0x000000e0
+#define CPG_FRQCRC_ZFC_MASK GENMASK(12, 8)
+
+struct cpg_z_clk {
+ struct clk_hw hw;
+ void __iomem *reg;
+ void __iomem *kick_reg;
+};
+
+#define to_z_clk(_hw) container_of(_hw, struct cpg_z_clk, hw)
+
+static unsigned long cpg_z_clk_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct cpg_z_clk *zclk = to_z_clk(hw);
+ unsigned int mult;
+
+ mult = 32 - FIELD_GET(CPG_FRQCRC_ZFC_MASK, clk_readl(zclk->reg));
+ return DIV_ROUND_CLOSEST_ULL(parent_rate * mult, 32);
+}
+
+static long cpg_z_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ unsigned long prate = *parent_rate;
+ unsigned int mult;
+
+ mult = div_u64((u64)rate * 32, prate);
+ mult = clamp(mult, 1U, 32U);
+
+ return *parent_rate * mult / 32;
+}
+
+static int cpg_z_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct cpg_z_clk *zclk = to_z_clk(hw);
+ unsigned int mult;
+ unsigned int i;
+ u32 val, kick;
+
+ mult = DIV_ROUND_CLOSEST_ULL(rate * 32ULL, parent_rate);
+ mult = clamp(mult, 1U, 32U);
+
+ if (clk_readl(zclk->kick_reg) & CPG_FRQCRB_KICK)
+ return -EBUSY;
+
+ val = clk_readl(zclk->reg) & ~CPG_FRQCRC_ZFC_MASK;
+ val |= FIELD_PREP(CPG_FRQCRC_ZFC_MASK, 32 - mult);
+ clk_writel(val, zclk->reg);
+
+ /*
+ * Set KICK bit in FRQCRB to update hardware setting and wait for
+ * clock change completion.
+ */
+ kick = clk_readl(zclk->kick_reg);
+ kick |= CPG_FRQCRB_KICK;
+ clk_writel(kick, zclk->kick_reg);
+
+ /*
+ * Note: There is no HW information about the worst case latency.
+ *
+ * Using experimental measurements, it seems that no more than
+ * ~10 iterations are needed, independently of the CPU rate.
+ * Since this value might be dependent of external xtal rate, pll1
+ * rate or even the other emulation clocks rate, use 1000 as a
+ * "super" safe value.
+ */
+ for (i = 1000; i; i--) {
+ if (!(clk_readl(zclk->kick_reg) & CPG_FRQCRB_KICK))
+ return 0;
+
+ cpu_relax();
+ }
+
+ return -ETIMEDOUT;
+}
+
+static const struct clk_ops cpg_z_clk_ops = {
+ .recalc_rate = cpg_z_clk_recalc_rate,
+ .round_rate = cpg_z_clk_round_rate,
+ .set_rate = cpg_z_clk_set_rate,
+};
+
+static struct clk * __init cpg_z_clk_register(const char *name,
+ const char *parent_name,
+ void __iomem *reg)
+{
+ struct clk_init_data init;
+ struct cpg_z_clk *zclk;
+ struct clk *clk;
+
+ zclk = kzalloc(sizeof(*zclk), GFP_KERNEL);
+ if (!zclk)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &cpg_z_clk_ops;
+ init.flags = 0;
+ init.parent_names = &parent_name;
+ init.num_parents = 1;
+
+ zclk->reg = reg + CPG_FRQCRC;
+ zclk->kick_reg = reg + CPG_FRQCRB;
+ zclk->hw.init = &init;
+
+ clk = clk_register(NULL, &zclk->hw);
+ if (IS_ERR(clk))
+ kfree(zclk);
+
+ return clk;
+}
/*
* SDn Clock
@@ -373,6 +497,10 @@ struct clk * __init rcar_gen3_cpg_clk_register(struct device *dev,
mult = 1;
break;
+ case CLK_TYPE_GEN3_Z:
+ return cpg_z_clk_register(core->name, __clk_get_name(parent),
+ base);
+
default:
return ERR_PTR(-EINVAL);
}
diff --git a/drivers/clk/renesas/rcar-gen3-cpg.h b/drivers/clk/renesas/rcar-gen3-cpg.h
index d756ef8b78eb..89da28f6f71b 100644
--- a/drivers/clk/renesas/rcar-gen3-cpg.h
+++ b/drivers/clk/renesas/rcar-gen3-cpg.h
@@ -21,6 +21,7 @@ enum rcar_gen3_clk_types {
CLK_TYPE_GEN3_SD,
CLK_TYPE_GEN3_R,
CLK_TYPE_GEN3_PE,
+ CLK_TYPE_GEN3_Z,
};
#define DEF_GEN3_SD(_name, _id, _parent, _offset) \
--
2.1.4
