[PATCH v2 10/10] clk: qcom: Fix .set_rate to handle alpha PLLs w/wo dynamic update

Rajendra Nayak
2016-08-11T08:42:34Z

From: Taniya Das <tdas@codeaurora.org>

Alpha PLLs which do not support dynamic update feature
need to be explicitly disabled before a rate change. The ones which do
support dynamic update don't have to be disabled but need to follow a update
sequence (as implemented by clk_alpha_pll_dynamic_update() in the patch).
They also need the PLL_HW_LOGIC_BYPASS bit set at init.

Signed-off-by: Taniya Das <tdas@codeaurora.org>
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
---
drivers/clk/qcom/clk-alpha-pll.c | 48 ++++++++++++++++++++++++++++++++++++++++
drivers/clk/qcom/clk-alpha-pll.h | 1 +
2 files changed, 49 insertions(+)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 2184dc1..68c90f3 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -113,6 +113,11 @@ static int wait_for_pll_offline(struct clk_alpha_pll *pll, u32 mask)
#define PLL_OFFLINE_ACK BIT(28)
#define PLL_ACTIVE_FLAG BIT(30)

+/* alpha pll with dynamic update support */
+#define PLL_UPDATE BIT(22)
+#define PLL_HW_LOGIC_BYPASS BIT(23)
+#define PLL_ACK_LATCH BIT(29)
+
void clk_alpha_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
const struct alpha_pll_config *config)
{
@@ -138,6 +143,37 @@ void clk_alpha_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
if (pll->flags & SUPPORTS_VOTE_FSM)
qcom_pll_set_fsm_mode(regmap, pll->offset + PLL_MODE, 6, 0);

+ if (pll->flags & SUPPORTS_DYNAMIC_UPDATE)
+ regmap_update_bits(regmap, pll->offset + PLL_MODE,
+ PLL_HW_LOGIC_BYPASS,
+ PLL_HW_LOGIC_BYPASS);
+}
+
+static int clk_alpha_pll_dynamic_update(struct clk_alpha_pll *pll)
+{
+ u32 val;
+
+ /* Latch the input to the PLL */
+ regmap_update_bits(pll->clkr.regmap, pll->offset + PLL_MODE,
+ PLL_UPDATE, PLL_UPDATE);
+
+ /* Wait for 2 reference cycle before checking ACK bit */
+ udelay(1);
+
+ regmap_read(pll->clkr.regmap, pll->offset + PLL_MODE, &val);
+ if (!(val & PLL_ACK_LATCH)) {
+ WARN(1, "PLL latch failed. Output may be unstable!\n");
+ return -EINVAL;
+ }
+
+ /* Return latch input to 0 */
+ regmap_update_bits(pll->clkr.regmap, pll->offset + PLL_MODE,
+ PLL_UPDATE, 0);
+
+ /* Wait for PLL output to stabilize */
+ udelay(100);
+
+ return 0;
}

static int clk_alpha_pll_hwfsm_enable(struct clk_hw *hw)
@@ -366,6 +402,7 @@ clk_alpha_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long prate)
{
+ int enabled;
struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
const struct pll_vco *vco;
u32 l, off = pll->offset;
@@ -378,6 +415,11 @@ static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
return -EINVAL;
}

+ enabled = hw->init->ops->is_enabled(hw);
+
+ if (!(pll->flags & SUPPORTS_DYNAMIC_UPDATE) && enabled)
+ hw->init->ops->disable(hw);
+
a <<= (ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH);

regmap_write(pll->clkr.regmap, off + PLL_L_VAL, l);
@@ -391,6 +433,12 @@ static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
regmap_update_bits(pll->clkr.regmap, off + PLL_USER_CTL, PLL_ALPHA_EN,
PLL_ALPHA_EN);

+ if (!(pll->flags & SUPPORTS_DYNAMIC_UPDATE) && enabled)
+ hw->init->ops->enable(hw);
+
+ if (pll->flags & SUPPORTS_DYNAMIC_UPDATE)
+ clk_alpha_pll_dynamic_update(pll);
+
return 0;
}

diff --git a/drivers/clk/qcom/clk-alpha-pll.h b/drivers/clk/qcom/clk-alpha-pll.h
index 4bd42fd..23e32db 100644
--- a/drivers/clk/qcom/clk-alpha-pll.h
+++ b/drivers/clk/qcom/clk-alpha-pll.h
@@ -36,6 +36,7 @@ struct clk_alpha_pll {
size_t num_vco;

#define SUPPORTS_VOTE_FSM BIT(0)
+#define SUPPORTS_DYNAMIC_UPDATE BIT(1)
u8 flags;
struct clk_regmap clkr;
};
--
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