From patchwork Tue Feb 8 18:34:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Martin_Povi=C5=A1er?= X-Patchwork-Id: 12739192 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C84E4C433FE for ; Tue, 8 Feb 2022 18:41:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231149AbiBHSlo (ORCPT ); Tue, 8 Feb 2022 13:41:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36360 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1385080AbiBHSlm (ORCPT ); Tue, 8 Feb 2022 13:41:42 -0500 X-Greylist: delayed 403 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 08 Feb 2022 10:41:39 PST Received: from hutie.ust.cz (unknown [IPv6:2a03:3b40:fe:f0::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 491C7C06157B; Tue, 8 Feb 2022 10:41:38 -0800 (PST) From: =?utf-8?q?Martin_Povi=C5=A1er?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cutebit.org; s=mail; t=1644345293; bh=C2NGAAeRS1YCWvvrFSmpGAh3DydYiDjAFK9L9+leUpc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JeiGA/04kSmNIliiS6qURc5WrrHFeD5HM19cMIol+99SI2mbVyrpdy+Au3LNMAU3A 4EOxX3eNiNUzgrgZg6dlGaGdtZkhflANXmGEEc9hAYJTGBp0d5XGdE4hKt12o+amcp G26rMrDeEEQKZMT/r0AjxOMfNnGcnEkP5lqJM2XU= To: Michael Turquette , Stephen Boyd , Rob Herring , Krzysztof Kozlowski Cc: Hector Martin , Sven Peter , Alyssa Rosenzweig , linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Kettenis , =?utf-8?q?Martin_Povi=C5=A1er?= Subject: [PATCH v4 2/3] clk: clk-apple-nco: Add driver for Apple NCO Date: Tue, 8 Feb 2022 19:34:10 +0100 Message-Id: <20220208183411.61090-3-povik+lin@cutebit.org> In-Reply-To: <20220208183411.61090-1-povik+lin@cutebit.org> References: <20220208183411.61090-1-povik+lin@cutebit.org> MIME-Version: 1.0 X-Spam: Yes Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org Add a common clock driver for NCO blocks found on Apple SoCs where they are typically the generators of audio clocks. Signed-off-by: Martin Povišer --- drivers/clk/Kconfig | 9 + drivers/clk/Makefile | 1 + drivers/clk/clk-apple-nco.c | 333 ++++++++++++++++++++++++++++++++++++ 3 files changed, 343 insertions(+) create mode 100644 drivers/clk/clk-apple-nco.c diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig index 3cdf33470a75..b945d3bb95d6 100644 --- a/drivers/clk/Kconfig +++ b/drivers/clk/Kconfig @@ -59,6 +59,15 @@ config LMK04832 Say yes here to build support for Texas Instruments' LMK04832 Ultra Low-Noise JESD204B Compliant Clock Jitter Cleaner With Dual Loop PLLs +config COMMON_CLK_APPLE_NCO + bool "Clock driver for Apple SoC NCOs" + depends on ARCH_APPLE || COMPILE_TEST + default ARCH_APPLE + help + This driver supports NCO (Numerically Controlled Oscillator) blocks + found on Apple SoCs such as t8103 (M1). The blocks are typically + generators of audio clocks. + config COMMON_CLK_MAX77686 tristate "Clock driver for Maxim 77620/77686/77802 MFD" depends on MFD_MAX77686 || MFD_MAX77620 || COMPILE_TEST diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index 6a98291350b6..45b6d8c51d61 100644 --- a/drivers/clk/Makefile +++ b/drivers/clk/Makefile @@ -18,6 +18,7 @@ endif # hardware specific clock types # please keep this section sorted lexicographically by file path name +obj-$(CONFIG_COMMON_CLK_APPLE_NCO) += clk-apple-nco.o obj-$(CONFIG_MACH_ASM9260) += clk-asm9260.o obj-$(CONFIG_COMMON_CLK_AXI_CLKGEN) += clk-axi-clkgen.o obj-$(CONFIG_ARCH_AXXIA) += clk-axm5516.o diff --git a/drivers/clk/clk-apple-nco.c b/drivers/clk/clk-apple-nco.c new file mode 100644 index 000000000000..d985a7be8947 --- /dev/null +++ b/drivers/clk/clk-apple-nco.c @@ -0,0 +1,333 @@ +// SPDX-License-Identifier: GPL-2.0-only OR MIT +/* + * Driver for an SoC block (Numerically Controlled Oscillator) + * found on t8103 (M1) and other Apple chips + * + * Copyright (C) The Asahi Linux Contributors + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define NCO_CHANNEL_STRIDE 0x4000 +#define NCO_CHANNEL_REGSIZE 20 + +#define REG_CTRL 0 +#define CTRL_ENABLE BIT(31) +#define REG_DIV 4 +#define DIV_FINE GENMASK(1, 0) +#define DIV_COARSE GENMASK(12, 2) +#define REG_INC1 8 +#define REG_INC2 12 +#define REG_ACCINIT 16 + +/* + * Theory of operation (postulated) + * + * The REG_DIV register indirectly expresses a base integer divisor, roughly + * corresponding to twice the desired ratio of input to output clock. This + * base divisor is adjusted on a cycle-by-cycle basis based on the state of a + * 32-bit phase accumulator to achieve a desired precise clock ratio over the + * long term. + * + * Specifically an output clock cycle is produced after (REG_DIV divisor)/2 + * or (REG_DIV divisor + 1)/2 input cycles, the latter taking effect when top + * bit of the 32-bit accumulator is set. The accumulator is incremented each + * produced output cycle, by the value from either REG_INC1 or REG_INC2, which + * of the two is selected depending again on the accumulator's current top bit. + * + * Because the NCO hardware implements counting of input clock cycles in part + * in a Galois linear-feedback shift register, the higher bits of divisor + * are programmed into REG_DIV by picking an appropriate LFSR state. See + * applnco_compute_tables/applnco_div_translate for details on this. + */ + +#define LFSR_POLY 0xa01 +#define LFSR_INIT 0x7ff +#define LFSR_LEN 11 +#define LFSR_PERIOD ((1 << LFSR_LEN) - 1) +#define LFSR_TBLSIZE (1 << LFSR_LEN) + +/* The minimal attainable coarse divisor (first value in table) */ +#define COARSE_DIV_OFFSET 2 + +struct applnco_tables { + u16 fwd[LFSR_TBLSIZE]; + u16 inv[LFSR_TBLSIZE]; +}; + +struct applnco_channel { + void __iomem *base; + struct applnco_tables *tbl; + struct clk_hw hw; + + spinlock_t lock; +}; + +#define to_applnco_channel(_hw) container_of(_hw, struct applnco_channel, hw) + +static void applnco_enable_nolock(struct clk_hw *hw) +{ + struct applnco_channel *chan = to_applnco_channel(hw); + u32 val; + + val = readl_relaxed(chan->base + REG_CTRL); + writel_relaxed(val | CTRL_ENABLE, chan->base + REG_CTRL); +} + +static void applnco_disable_nolock(struct clk_hw *hw) +{ + struct applnco_channel *chan = to_applnco_channel(hw); + u32 val; + + val = readl_relaxed(chan->base + REG_CTRL); + writel_relaxed(val & ~CTRL_ENABLE, chan->base + REG_CTRL); +} + +static int applnco_is_enabled(struct clk_hw *hw) +{ + struct applnco_channel *chan = to_applnco_channel(hw); + + return (readl_relaxed(chan->base + REG_CTRL) & CTRL_ENABLE) != 0; +} + +static void applnco_compute_tables(struct applnco_tables *tbl) +{ + int i; + u32 state = LFSR_INIT; + + /* + * Go through the states of a Galois LFSR and build + * a coarse divisor translation table. + */ + for (i = LFSR_PERIOD; i > 0; i--) { + if (state & 1) + state = (state >> 1) ^ (LFSR_POLY >> 1); + else + state = (state >> 1); + tbl->fwd[i] = state; + tbl->inv[state] = i; + } + + /* Zero value is special-cased */ + tbl->fwd[0] = 0; + tbl->inv[0] = 0; +} + +static bool applnco_div_out_of_range(unsigned int div) +{ + unsigned int coarse = div / 4; + + return coarse < COARSE_DIV_OFFSET || + coarse >= COARSE_DIV_OFFSET + LFSR_TBLSIZE; +} + +static u32 applnco_div_translate(struct applnco_tables *tbl, unsigned int div) +{ + unsigned int coarse = div / 4; + + if (WARN_ON(applnco_div_out_of_range(div))) + return 0; + + return FIELD_PREP(DIV_COARSE, tbl->fwd[coarse - COARSE_DIV_OFFSET]) | + FIELD_PREP(DIV_FINE, div % 4); +} + +static unsigned int applnco_div_translate_inv(struct applnco_tables *tbl, u32 regval) +{ + unsigned int coarse, fine; + + coarse = tbl->inv[FIELD_GET(DIV_COARSE, regval)] + COARSE_DIV_OFFSET; + fine = FIELD_GET(DIV_FINE, regval); + + return coarse * 4 + fine; +} + +static int applnco_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct applnco_channel *chan = to_applnco_channel(hw); + unsigned long flags; + u32 div, inc1, inc2; + bool was_enabled; + + div = 2 * parent_rate / rate; + inc1 = 2 * parent_rate - div * rate; + inc2 = inc1 - rate; + + if (applnco_div_out_of_range(div)) + return -EINVAL; + + div = applnco_div_translate(chan->tbl, div); + + spin_lock_irqsave(&chan->lock, flags); + was_enabled = applnco_is_enabled(hw); + applnco_disable_nolock(hw); + + writel_relaxed(div, chan->base + REG_DIV); + writel_relaxed(inc1, chan->base + REG_INC1); + writel_relaxed(inc2, chan->base + REG_INC2); + + /* Presumably a neutral initial value for accumulator */ + writel_relaxed(1 << 31, chan->base + REG_ACCINIT); + + if (was_enabled) + applnco_enable_nolock(hw); + spin_unlock_irqrestore(&chan->lock, flags); + + return 0; +} + +static unsigned long applnco_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct applnco_channel *chan = to_applnco_channel(hw); + u32 div, inc1, inc2, incbase; + + div = applnco_div_translate_inv(chan->tbl, + readl_relaxed(chan->base + REG_DIV)); + + inc1 = readl_relaxed(chan->base + REG_INC1); + inc2 = readl_relaxed(chan->base + REG_INC2); + + /* + * We don't support wraparound of accumulator + * nor the edge case of both increments being zero + */ + if (inc1 >= (1 << 31) || inc2 < (1 << 31) || (inc1 == 0 && inc2 == 0)) + return 0; + + /* Scale both sides of division by incbase to maintain precision */ + incbase = inc1 - inc2; + + return div64_u64(((u64) parent_rate) * 2 * incbase, + ((u64) div) * incbase + inc1); +} + +static long applnco_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + unsigned long lo = *parent_rate / (COARSE_DIV_OFFSET + LFSR_TBLSIZE) + 1; + unsigned long hi = *parent_rate / COARSE_DIV_OFFSET; + + return clamp(rate, lo, hi); +} + +static int applnco_enable(struct clk_hw *hw) +{ + struct applnco_channel *chan = to_applnco_channel(hw); + unsigned long flags; + + spin_lock_irqsave(&chan->lock, flags); + applnco_enable_nolock(hw); + spin_unlock_irqrestore(&chan->lock, flags); + + return 0; +} + +static void applnco_disable(struct clk_hw *hw) +{ + struct applnco_channel *chan = to_applnco_channel(hw); + unsigned long flags; + + spin_lock_irqsave(&chan->lock, flags); + applnco_disable_nolock(hw); + spin_unlock_irqrestore(&chan->lock, flags); +} + +static const struct clk_ops applnco_ops = { + .set_rate = applnco_set_rate, + .recalc_rate = applnco_recalc_rate, + .round_rate = applnco_round_rate, + .enable = applnco_enable, + .disable = applnco_disable, + .is_enabled = applnco_is_enabled, +}; + +static int applnco_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct clk_parent_data pdata = { .index = 0 }; + struct clk_init_data init; + struct clk_hw_onecell_data *onecell_data; + void __iomem *base; + struct resource *res; + struct applnco_tables *tbl; + unsigned int nchannels; + int ret, i; + + base = devm_platform_get_and_ioremap_resource(pdev, 0, &res); + if (IS_ERR(base)) + return PTR_ERR(base); + + if (resource_size(res) < NCO_CHANNEL_REGSIZE) + return -EINVAL; + nchannels = (resource_size(res) - NCO_CHANNEL_REGSIZE) + / NCO_CHANNEL_STRIDE + 1; + + onecell_data = devm_kzalloc(&pdev->dev, struct_size(onecell_data, hws, + nchannels), GFP_KERNEL); + if (!onecell_data) + return -ENOMEM; + onecell_data->num = nchannels; + + tbl = devm_kzalloc(&pdev->dev, sizeof(*tbl), GFP_KERNEL); + if (!tbl) + return -ENOMEM; + applnco_compute_tables(tbl); + + for (i = 0; i < nchannels; i++) { + struct applnco_channel *chan; + + chan = devm_kzalloc(&pdev->dev, sizeof(*chan), GFP_KERNEL); + if (!chan) + return -ENOMEM; + chan->base = base + NCO_CHANNEL_STRIDE * i; + chan->tbl = tbl; + spin_lock_init(&chan->lock); + + memset(&init, 0, sizeof(init)); + init.name = devm_kasprintf(&pdev->dev, GFP_KERNEL, + "%s-%d", np->name, i); + init.ops = &applnco_ops; + init.parent_data = &pdata; + init.num_parents = 1; + init.flags = 0; + + chan->hw.init = &init; + ret = devm_clk_hw_register(&pdev->dev, &chan->hw); + if (ret) + return ret; + + onecell_data->hws[i] = &chan->hw; + } + + return devm_of_clk_add_hw_provider(&pdev->dev, of_clk_hw_onecell_get, + onecell_data); +} + +static const struct of_device_id applnco_ids[] = { + { .compatible = "apple,nco" }, + { } +}; +MODULE_DEVICE_TABLE(of, applnco_ids) + +static struct platform_driver applnco_driver = { + .driver = { + .name = "apple-nco", + .of_match_table = applnco_ids, + }, + .probe = applnco_probe, +}; +module_platform_driver(applnco_driver); + +MODULE_AUTHOR("Martin Povišer "); +MODULE_DESCRIPTION("Clock driver for NCO blocks on Apple SoCs"); +MODULE_LICENSE("GPL");