clk: analogbits: add Wide-Range PLL library

Add common library code for the Analog Bits Wide-Range PLL (WRPLL) IP
block, as implemented in TSMC CLN28HPC.

There is no bus interface or register target associated with this PLL.
This library is intended to be used by drivers for IP blocks that
expose registers connected to the PLL configuration and status
signals.

Based on code originally written by Wesley Terpstra
<wesley@sifive.com>:
https://github.com/riscv/riscv-linux/commit/999529edf517ed75b56659d456d221b2ee56bb60

This version incorporates several changes requested by Stephen
Boyd <sboyd@kernel.org>.

Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Wesley Terpstra <wesley@sifive.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Megan Wachs <megan@sifive.com>
Cc: linux-clk@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
[sboyd@kernel.org: Fix some const issues]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

1 files changed, 79 insertions, 0 deletions

diff --git a/include/linux/clk/analogbits-wrpll-cln28hpc.h b/include/linux/clk/analogbits-wrpll-cln28hpc.h
new file mode 100644
index 000000000000..03279097e138
--- /dev/null
+++ b/include/linux/clk/analogbits-wrpll-cln28hpc.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018-2019 SiFive, Inc.
+ * Wesley Terpstra
+ * Paul Walmsley
+ */
+
+#ifndef __LINUX_CLK_ANALOGBITS_WRPLL_CLN28HPC_H
+#define __LINUX_CLK_ANALOGBITS_WRPLL_CLN28HPC_H
+
+#include <linux/types.h>
+
+/* DIVQ_VALUES: number of valid DIVQ values */
+#define DIVQ_VALUES				6
+
+/*
+ * Bit definitions for struct wrpll_cfg.flags
+ *
+ * WRPLL_FLAGS_BYPASS_FLAG: if set, the PLL is either in bypass, or should be
+ *	programmed to enter bypass
+ * WRPLL_FLAGS_RESET_FLAG: if set, the PLL is in reset
+ * WRPLL_FLAGS_INT_FEEDBACK_FLAG: if set, the PLL is configured for internal
+ *	feedback mode
+ * WRPLL_FLAGS_EXT_FEEDBACK_FLAG: if set, the PLL is configured for external
+ *	feedback mode (not yet supported by this driver)
+ */
+#define WRPLL_FLAGS_BYPASS_SHIFT		0
+#define WRPLL_FLAGS_BYPASS_MASK		BIT(WRPLL_FLAGS_BYPASS_SHIFT)
+#define WRPLL_FLAGS_RESET_SHIFT		1
+#define WRPLL_FLAGS_RESET_MASK		BIT(WRPLL_FLAGS_RESET_SHIFT)
+#define WRPLL_FLAGS_INT_FEEDBACK_SHIFT	2
+#define WRPLL_FLAGS_INT_FEEDBACK_MASK	BIT(WRPLL_FLAGS_INT_FEEDBACK_SHIFT)
+#define WRPLL_FLAGS_EXT_FEEDBACK_SHIFT	3
+#define WRPLL_FLAGS_EXT_FEEDBACK_MASK	BIT(WRPLL_FLAGS_EXT_FEEDBACK_SHIFT)
+
+/**
+ * struct wrpll_cfg - WRPLL configuration values
+ * @divr: reference divider value (6 bits), as presented to the PLL signals
+ * @divf: feedback divider value (9 bits), as presented to the PLL signals
+ * @divq: output divider value (3 bits), as presented to the PLL signals
+ * @flags: PLL configuration flags.  See above for more information
+ * @range: PLL loop filter range.  See below for more information
+ * @output_rate_cache: cached output rates, swept across DIVQ
+ * @parent_rate: PLL refclk rate for which values are valid
+ * @max_r: maximum possible R divider value, given @parent_rate
+ * @init_r: initial R divider value to start the search from
+ *
+ * @divr, @divq, @divq, @range represent what the PLL expects to see
+ * on its input signals.  Thus @divr and @divf are the actual divisors
+ * minus one.  @divq is a power-of-two divider; for example, 1 =
+ * divide-by-2 and 6 = divide-by-64.  0 is an invalid @divq value.
+ *
+ * When initially passing a struct wrpll_cfg record, the
+ * record should be zero-initialized with the exception of the @flags
+ * field.  The only flag bits that need to be set are either
+ * WRPLL_FLAGS_INT_FEEDBACK or WRPLL_FLAGS_EXT_FEEDBACK.
+ */
+struct wrpll_cfg {
+	u8 divr;
+	u8 divq;
+	u8 range;
+	u8 flags;
+	u16 divf;
+/* private: */
+	u32 output_rate_cache[DIVQ_VALUES];
+	unsigned long parent_rate;
+	u8 max_r;
+	u8 init_r;
+};
+
+int wrpll_configure_for_rate(struct wrpll_cfg *c, u32 target_rate,
+			     unsigned long parent_rate);
+
+unsigned int wrpll_calc_max_lock_us(const struct wrpll_cfg *c);
+
+unsigned long wrpll_calc_output_rate(const struct wrpll_cfg *c,
+				     unsigned long parent_rate);
+
+#endif /* __LINUX_CLK_ANALOGBITS_WRPLL_CLN28HPC_H */