From: Jernej Skrabec <jernej.skrabec@siol.net>
To: mripard@kernel.org, wens@csie.org
Cc: mturquette@baylibre.com, sboyd@kernel.org,
linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com
Subject: [PATCH] clk: sunxi-ng: sun8i: r40: Use sigma delta modulation for audio PLL
Date: Tue, 25 Aug 2020 15:10:49 +0200 [thread overview]
Message-ID: <20200825131049.1277596-1-jernej.skrabec@siol.net> (raw)
Audio cores need specific clock rates which can't be simply obtained by
adjusting integer multipliers and dividers. HW for such cases supports
delta-sigma modulation which enables fractional multipliers.
Port H3 delta-sigma table to R40. They have identical audio PLLs.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
---
drivers/clk/sunxi-ng/ccu-sun8i-r40.c | 37 ++++++++++++++++++----------
1 file changed, 24 insertions(+), 13 deletions(-)
diff --git a/drivers/clk/sunxi-ng/ccu-sun8i-r40.c b/drivers/clk/sunxi-ng/ccu-sun8i-r40.c
index 23bfe1d12f21..84153418453f 100644
--- a/drivers/clk/sunxi-ng/ccu-sun8i-r40.c
+++ b/drivers/clk/sunxi-ng/ccu-sun8i-r40.c
@@ -45,18 +45,29 @@ static struct ccu_nkmp pll_cpu_clk = {
* the base (2x, 4x and 8x), and one variable divider (the one true
* pll audio).
*
- * We don't have any need for the variable divider for now, so we just
- * hardcode it to match with the clock names
+ * With sigma-delta modulation for fractional-N on the audio PLL,
+ * we have to use specific dividers. This means the variable divider
+ * can no longer be used, as the audio codec requests the exact clock
+ * rates we support through this mechanism. So we now hard code the
+ * variable divider to 1. This means the clock rates will no longer
+ * match the clock names.
*/
#define SUN8I_R40_PLL_AUDIO_REG 0x008
-static SUNXI_CCU_NM_WITH_GATE_LOCK(pll_audio_base_clk, "pll-audio-base",
- "osc24M", 0x008,
- 8, 7, /* N */
- 0, 5, /* M */
- BIT(31), /* gate */
- BIT(28), /* lock */
- CLK_SET_RATE_UNGATE);
+static struct ccu_sdm_setting pll_audio_sdm_table[] = {
+ { .rate = 22579200, .pattern = 0xc0010d84, .m = 8, .n = 7 },
+ { .rate = 24576000, .pattern = 0xc000ac02, .m = 14, .n = 14 },
+};
+
+static SUNXI_CCU_NM_WITH_SDM_GATE_LOCK(pll_audio_base_clk, "pll-audio-base",
+ "osc24M", 0x008,
+ 8, 7, /* N */
+ 0, 5, /* M */
+ pll_audio_sdm_table, BIT(24),
+ 0x284, BIT(31),
+ BIT(31), /* gate */
+ BIT(28), /* lock */
+ CLK_SET_RATE_UNGATE);
static SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX(pll_video0_clk, "pll-video0",
"osc24M", 0x0010,
@@ -952,10 +963,10 @@ static const struct clk_hw *clk_parent_pll_audio[] = {
&pll_audio_base_clk.common.hw
};
-/* We hardcode the divider to 4 for now */
+/* We hardcode the divider to 1 for now */
static CLK_FIXED_FACTOR_HWS(pll_audio_clk, "pll-audio",
clk_parent_pll_audio,
- 4, 1, CLK_SET_RATE_PARENT);
+ 1, 1, CLK_SET_RATE_PARENT);
static CLK_FIXED_FACTOR_HWS(pll_audio_2x_clk, "pll-audio-2x",
clk_parent_pll_audio,
2, 1, CLK_SET_RATE_PARENT);
@@ -1307,10 +1318,10 @@ static int sun8i_r40_ccu_probe(struct platform_device *pdev)
if (IS_ERR(reg))
return PTR_ERR(reg);
- /* Force the PLL-Audio-1x divider to 4 */
+ /* Force the PLL-Audio-1x divider to 1 */
val = readl(reg + SUN8I_R40_PLL_AUDIO_REG);
val &= ~GENMASK(19, 16);
- writel(val | (3 << 16), reg + SUN8I_R40_PLL_AUDIO_REG);
+ writel(val | (0 << 16), reg + SUN8I_R40_PLL_AUDIO_REG);
/* Force PLL-MIPI to MIPI mode */
val = readl(reg + SUN8I_R40_PLL_MIPI_REG);
--
2.28.0
next reply other threads:[~2020-08-25 13:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 13:10 Jernej Skrabec [this message]
2020-08-25 14:43 ` [PATCH] clk: sunxi-ng: sun8i: r40: Use sigma delta modulation for audio PLL Maxime Ripard
2020-08-25 14:46 ` [linux-sunxi] " Chen-Yu Tsai
2020-08-25 16:45 ` Jernej Škrabec
2020-08-25 16:47 ` Chen-Yu Tsai
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