arm: mach-snapdragon: refactor clock driver

In preparation to add support for the Dragonboard820c (APQ8096),
refactor the current Snapdragon clock driver.

No new functionality has been added.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
diff --git a/arch/arm/mach-snapdragon/clock-snapdragon.c b/arch/arm/mach-snapdragon/clock-snapdragon.c
new file mode 100644
index 0000000..899b5ba
--- /dev/null
+++ b/arch/arm/mach-snapdragon/clock-snapdragon.c
@@ -0,0 +1,134 @@
+/*
+ * Clock drivers for Qualcomm APQ8016, APQ8096
+ *
+ * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
+ *
+ * Based on Little Kernel driver, simplified
+ *
+ * SPDX-License-Identifier:	BSD-3-Clause
+ */
+
+#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"
+
+/* CBCR register fields */
+#define CBCR_BRANCH_ENABLE_BIT  BIT(0)
+#define CBCR_BRANCH_OFF_BIT     BIT(31)
+
+extern ulong msm_set_rate(struct clk *clk, ulong rate);
+
+/* Enable clock controlled by CBC soft macro */
+void clk_enable_cbc(phys_addr_t cbcr)
+{
+	setbits_le32(cbcr, CBCR_BRANCH_ENABLE_BIT);
+
+	while (readl(cbcr) & CBCR_BRANCH_OFF_BIT)
+		;
+}
+
+void clk_enable_gpll0(phys_addr_t base, const struct gpll0_ctrl *gpll0)
+{
+	if (readl(base + gpll0->status) & gpll0->status_bit)
+		return; /* clock already enabled */
+
+	setbits_le32(base + gpll0->ena_vote, gpll0->vote_bit);
+
+	while ((readl(base + gpll0->status) & gpll0->status_bit) == 0)
+		;
+}
+
+#define APPS_CMD_RGCR_UPDATE BIT(0)
+
+/* Update clock command via CMD_RGCR */
+void clk_bcr_update(phys_addr_t apps_cmd_rgcr)
+{
+	setbits_le32(apps_cmd_rgcr, APPS_CMD_RGCR_UPDATE);
+
+	/* Wait for frequency to be updated. */
+	while (readl(apps_cmd_rgcr) & APPS_CMD_RGCR_UPDATE)
+		;
+}
+
+#define CFG_MODE_DUAL_EDGE (0x2 << 12) /* Counter mode */
+
+#define CFG_MASK 0x3FFF
+
+#define CFG_DIVIDER_MASK 0x1F
+
+/* root set rate for clocks with half integer and MND divider */
+void clk_rcg_set_rate_mnd(phys_addr_t base, const struct bcr_regs *regs,
+			  int div, int m, int n, int source)
+{
+	u32 cfg;
+	/* M value for MND divider. */
+	u32 m_val = m;
+	/* NOT(N-M) value for MND divider. */
+	u32 n_val = ~((n) - (m)) * !!(n);
+	/* NOT 2D value for MND divider. */
+	u32 d_val = ~(n);
+
+	/* Program MND values */
+	writel(m_val, base + regs->M);
+	writel(n_val, base + regs->N);
+	writel(d_val, base + regs->D);
+
+	/* setup src select and divider */
+	cfg  = readl(base + regs->cfg_rcgr);
+	cfg &= ~CFG_MASK;
+	cfg |= source & CFG_CLK_SRC_MASK; /* Select clock source */
+
+	/* Set the divider; HW permits fraction dividers (+0.5), but
+	   for simplicity, we will support integers only */
+	if (div)
+		cfg |= (2 * div - 1) & CFG_DIVIDER_MASK;
+
+	if (n_val)
+		cfg |= CFG_MODE_DUAL_EDGE;
+
+	writel(cfg, base + regs->cfg_rcgr); /* Write new clock configuration */
+
+	/* Inform h/w to start using the new config. */
+	clk_bcr_update(base + regs->cmd_rcgr);
+}
+
+static int msm_clk_probe(struct udevice *dev)
+{
+	struct msm_clk_priv *priv = dev_get_priv(dev);
+
+	priv->base = devfdt_get_addr(dev);
+	if (priv->base == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	return 0;
+}
+
+static ulong msm_clk_set_rate(struct clk *clk, ulong rate)
+{
+	return msm_set_rate(clk, rate);
+}
+
+static struct clk_ops msm_clk_ops = {
+	.set_rate = msm_clk_set_rate,
+};
+
+static const struct udevice_id msm_clk_ids[] = {
+	{ .compatible = "qcom,gcc-msm8916" },
+	{ .compatible = "qcom,gcc-apq8016" },
+	{ .compatible = "qcom,gcc-msm8996" },
+	{ .compatible = "qcom,gcc-apq8096" },
+	{ }
+};
+
+U_BOOT_DRIVER(clk_msm) = {
+	.name		= "clk_msm",
+	.id		= UCLASS_CLK,
+	.of_match	= msm_clk_ids,
+	.ops		= &msm_clk_ops,
+	.priv_auto_alloc_size = sizeof(struct msm_clk_priv),
+	.probe		= msm_clk_probe,
+};