[PATCH 4/6] clocks: qcom: add clocks for SDM845 debug uart

[Dzmitry Sankouski <dsankouski@gmail.com>]

Allows to change clock frequency of debug uart,
thus supporting wide range of baudrates.
Enable / disable functionality is not implemented yet.
In most use cases of SDM845 (i.e. mobile phones and tablets)
it's not needed, because qualcomm first stage bootloader leaves it
initialized, and on the other hand there's no possibility to
replace signed first stage bootloader with u-boot.

Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com>
Cc: Ramon Fried <rfried.dev@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
---
 arch/arm/mach-snapdragon/clock-sdm845.c     | 92 +++++++++++++++++++++
 arch/arm/mach-snapdragon/clock-snapdragon.c |  1 +
 arch/arm/mach-snapdragon/clock-snapdragon.h |  3 +-
 3 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm/mach-snapdragon/clock-sdm845.c

diff --git a/arch/arm/mach-snapdragon/clock-sdm845.c b/arch/arm/mach-snapdragon/clock-sdm845.c
new file mode 100644
index 0000000000..9572639238
--- /dev/null
+++ b/arch/arm/mach-snapdragon/clock-sdm845.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Clock drivers for Qualcomm SDM845
+ *
+ * (C) Copyright 2017 Jorge Ramirez Ortiz <jorge.ramirez-ortiz@linaro.org>
+ * (C) Copyright 2021 Dzmitry Sankouski <dsankouski@gmail.com>
+ *
+ * Based on Little Kernel driver, simplified
+ */
+
+#include <common.h>
+#include <clk-uclass.h>
+#include <dm.h>
+#include <errno.h>
+#include <asm/io.h>
+#include <linux/bitops.h>
+#include "clock-snapdragon.h"
+
+#define F(f, s, h, m, n) { (f), (s), (2 * (h) - 1), (m), (n) }
+
+struct freq_tbl {
+	uint freq;
+	uint src;
+	u8 pre_div;
+	u16 m;
+	u16 n;
+};
+
+static const struct freq_tbl ftbl_gcc_qupv3_wrap0_s0_clk_src[] = {
+	F(7372800, CFG_CLK_SRC_GPLL0_EVEN, 1, 384, 15625),
+	F(14745600, CFG_CLK_SRC_GPLL0_EVEN, 1, 768, 15625),
+	F(19200000, CFG_CLK_SRC_CXO, 1, 0, 0),
+	F(29491200, CFG_CLK_SRC_GPLL0_EVEN, 1, 1536, 15625),
+	F(32000000, CFG_CLK_SRC_GPLL0_EVEN, 1, 8, 75),
+	F(48000000, CFG_CLK_SRC_GPLL0_EVEN, 1, 4, 25),
+	F(64000000, CFG_CLK_SRC_GPLL0_EVEN, 1, 16, 75),
+	F(80000000, CFG_CLK_SRC_GPLL0_EVEN, 1, 4, 15),
+	F(96000000, CFG_CLK_SRC_GPLL0_EVEN, 1, 8, 25),
+	F(100000000, CFG_CLK_SRC_GPLL0_EVEN, 3, 0, 0),
+	F(102400000, CFG_CLK_SRC_GPLL0_EVEN, 1, 128, 375),
+	F(112000000, CFG_CLK_SRC_GPLL0_EVEN, 1, 28, 75),
+	F(117964800, CFG_CLK_SRC_GPLL0_EVEN, 1, 6144, 15625),
+	F(120000000, CFG_CLK_SRC_GPLL0_EVEN, 2.5, 0, 0),
+	F(128000000, CFG_CLK_SRC_GPLL0, 1, 16, 75),
+	{ }
+};
+
+static const struct bcr_regs uart2_regs = {
+	.cfg_rcgr = SE9_UART_APPS_CFG_RCGR,
+	.cmd_rcgr = SE9_UART_APPS_CMD_RCGR,
+	.M = SE9_UART_APPS_M,
+	.N = SE9_UART_APPS_N,
+	.D = SE9_UART_APPS_D,
+};
+
+const struct freq_tbl *qcom_find_freq(const struct freq_tbl *f, uint rate)
+{
+	if (!f)
+		return NULL;
+
+	if (!f->freq)
+		return f;
+
+	for (; f->freq; f++)
+		if (rate <= f->freq)
+			return f;
+
+	/* Default to our fastest rate */
+	return f - 1;
+}
+
+static int clk_init_uart(struct msm_clk_priv *priv, uint rate)
+{
+	const struct freq_tbl *freq = qcom_find_freq(ftbl_gcc_qupv3_wrap0_s0_clk_src, rate);
+
+	clk_rcg_set_rate_mnd(priv->base, &uart2_regs,
+						freq->pre_div, freq->m, freq->n, freq->src);
+
+	return 0;
+}
+
+ulong msm_set_rate(struct clk *clk, ulong rate)
+{
+	struct msm_clk_priv *priv = dev_get_priv(clk->dev);
+
+	switch (clk->id) {
+	case 0x58: /*UART2*/
+		return clk_init_uart(priv, rate);
+	default:
+		return 0;
+	}
+}
diff --git a/arch/arm/mach-snapdragon/clock-snapdragon.c b/arch/arm/mach-snapdragon/clock-snapdragon.c
index 2b76371718..3deb08ac4a 100644
--- a/arch/arm/mach-snapdragon/clock-snapdragon.c
+++ b/arch/arm/mach-snapdragon/clock-snapdragon.c
@@ -135,6 +135,7 @@ static const struct udevice_id msm_clk_ids[] = {
 	{ .compatible = "qcom,gcc-apq8016" },
 	{ .compatible = "qcom,gcc-msm8996" },
 	{ .compatible = "qcom,gcc-apq8096" },
+	{ .compatible = "qcom,gcc-sdm845" },
 	{ }
 };
 
diff --git a/arch/arm/mach-snapdragon/clock-snapdragon.h b/arch/arm/mach-snapdragon/clock-snapdragon.h
index 58fab40a2e..2ac53b538d 100644
--- a/arch/arm/mach-snapdragon/clock-snapdragon.h
+++ b/arch/arm/mach-snapdragon/clock-snapdragon.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0+ */
 /*
- * Qualcomm APQ8016, APQ8096
+ * Qualcomm APQ8016, APQ8096, SDM845
  *
  * (C) Copyright 2017 Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
  */
@@ -9,6 +9,7 @@
 
 #define CFG_CLK_SRC_CXO   (0 << 8)
 #define CFG_CLK_SRC_GPLL0 (1 << 8)
+#define CFG_CLK_SRC_GPLL0_EVEN (6 << 8)
 #define CFG_CLK_SRC_MASK  (7 << 8)
 
 struct pll_vote_clk {
-- 
2.20.1