Re: [PATCH v2 4/7] clk: qcom: clk-alpha-pll: Add support for controlling Lucid PLLs
From: Stephen Boyd <sboyd@kernel.org>
Date: 2020-02-05 19:33:55
Also in:
linux-arm-msm, linux-clk, linux-devicetree, lkml
Quoting Venkata Narendra Kumar Gutta (2020-01-24 14:32:24)
quoted hunk ↗ jump to hunk
diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c index 1b073b2..4258ab0 100644 --- a/drivers/clk/qcom/clk-alpha-pll.c +++ b/drivers/clk/qcom/clk-alpha-pll.c@@ -1367,3 +1388,172 @@ static int clk_alpha_pll_postdiv_fabia_set_rate(struct clk_hw *hw, .set_rate = clk_alpha_pll_postdiv_fabia_set_rate, }; EXPORT_SYMBOL_GPL(clk_alpha_pll_postdiv_fabia_ops); + +void clk_lucid_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
Can we get some kernel documentation for this function?
+ const struct alpha_pll_config *config)
+{
+ if (config->l)
+ regmap_write(regmap, PLL_L_VAL(pll), config->l);
+
+ regmap_write(regmap, PLL_CAL_L_VAL(pll), LUCID_PLL_CAL_VAL);
+
+ if (config->alpha)
+ regmap_write(regmap, PLL_ALPHA_VAL(pll), config->alpha);
+
+ if (config->config_ctl_val)
+ regmap_write(regmap, PLL_CONFIG_CTL(pll),
+ config->config_ctl_val);
+
+ if (config->config_ctl_hi_val)
+ regmap_write(regmap, PLL_CONFIG_CTL_U(pll),
+ config->config_ctl_hi_val);
+
+ if (config->config_ctl_hi1_val)
+ regmap_write(regmap, PLL_CONFIG_CTL_U1(pll),
+ config->config_ctl_hi1_val);
+
+ if (config->user_ctl_val)
+ regmap_write(regmap, PLL_USER_CTL(pll),
+ config->user_ctl_val);
+
+ if (config->user_ctl_hi_val)
+ regmap_write(regmap, PLL_USER_CTL_U(pll),
+ config->user_ctl_hi_val);
+
+ if (config->user_ctl_hi1_val)
+ regmap_write(regmap, PLL_USER_CTL_U1(pll),
+ config->user_ctl_hi1_val);
+
+ if (config->test_ctl_val)
+ regmap_write(regmap, PLL_TEST_CTL(pll),
+ config->test_ctl_val);
+
+ if (config->test_ctl_hi_val)
+ regmap_write(regmap, PLL_TEST_CTL_U(pll),
+ config->test_ctl_hi_val);
+
+ if (config->test_ctl_hi1_val)
+ regmap_write(regmap, PLL_TEST_CTL_U1(pll),
+ config->test_ctl_hi1_val);
+
+ regmap_update_bits(regmap, PLL_MODE(pll), PLL_UPDATE_BYPASS,
+ PLL_UPDATE_BYPASS);
+
+ /* Disable PLL output */
+ regmap_update_bits(regmap, PLL_MODE(pll), PLL_OUTCTRL, 0);
+
+ /* Set operation mode to OFF */
+ regmap_write(regmap, PLL_OPMODE(pll), PLL_STANDBY);
+
+ /* PLL should be in OFF mode before continuing */
+ wmb();How does the write above overtake the write below? This barrier looks wrong.
+
+ /* Place the PLL in STANDBY mode */
+ regmap_update_bits(regmap, PLL_MODE(pll), PLL_RESET_N, PLL_RESET_N);
+}
+EXPORT_SYMBOL_GPL(clk_lucid_pll_configure);
+
+/*
+ * The Lucid PLL requires a power-on self-calibration which happens when the
+ * PLL comes out of reset. Calibrate in case it is not completed.
+ */
+static int alpha_pll_lucid_prepare(struct clk_hw *hw)
+{
+ struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+ u32 regval;
+ int ret;
+
+ /* Return early if calibration is not needed. */
+ regmap_read(pll->clkr.regmap, PLL_STATUS(pll), ®val);
+ if (regval & LUCID_PCAL_DONE)
+ return 0;
+
+ ret = clk_trion_pll_enable(hw);
+ if (ret)
+ return ret;
+
+ clk_trion_pll_disable(hw);
+
+ return 0;Can you write this like: /* On/off to calibrate */ ret = clk_trion_pll_enable(hw); if (!ret) clk_trion_pll_disable(hw); return ret;
+}
+
+static int alpha_pll_lucid_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long prate)
+{
+ struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+ unsigned long rrate;
+ u32 regval, l, alpha_width = pll_alpha_width(pll);
+ u64 a;
+ int ret;
+
+ rrate = alpha_pll_round_rate(rate, prate, &l, &a, alpha_width);
+
+ /*
+ * Due to a limited number of bits for fractional rate programming, the
+ * rounded up rate could be marginally higher than the requested rate.
+ */
+ if (rrate > (rate + PLL_RATE_MARGIN) || rrate < rate) {Any chance this can be pushed into the alpha_pll_round_rate() API? It's duplicated in this driver.
+ pr_err("Call set rate on the PLL with rounded rates!\n");
+ return -EINVAL;
+ }
+
+ regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
+ regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
+
+ /* Latch the PLL input */
+ ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll),
+ PLL_UPDATE, PLL_UPDATE);
+ if (ret)
+ return ret;
+
+ /* Wait for 2 reference cycles before checking the ACK bit. */Are reference cycles 2 * 1 / 19.2MHz?
+ udelay(1);
+ regmap_read(pll->clkr.regmap, PLL_MODE(pll), ®val);
+ if (!(regval & ALPHA_PLL_ACK_LATCH)) {
+ WARN(1, "PLL latch failed. Output may be unstable!\n");Do we need a big WARN stack for this? How about pr_warn() instead?
+ return -EINVAL;
+ }
+
+ /* Return the latch input to 0 */
+ ret = regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll),
+ PLL_UPDATE, 0);
+ if (ret)
+ return ret;
+
+ if (clk_hw_is_enabled(hw)) {
+ ret = wait_for_pll_enable_lock(pll);
+ if (ret)
+ return ret;
+ }
+
+ /* Wait for PLL output to stabilize */
+ udelay(100);
+ return 0;
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