From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E330DC433DF for ; Wed, 27 May 2020 14:29:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF55020873 for ; Wed, 27 May 2020 14:29:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b="O0jUxeP7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389258AbgE0O31 (ORCPT ); Wed, 27 May 2020 10:29:27 -0400 Received: from esa1.microchip.iphmx.com ([68.232.147.91]:37714 "EHLO esa1.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389185AbgE0O30 (ORCPT ); Wed, 27 May 2020 10:29:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1590589764; x=1622125764; h=references:from:to:cc:subject:in-reply-to:date: message-id:mime-version; bh=SKXiRRaVA/1CryPTkYRSTd5BHlhiXuPPmD9xaF1+t9s=; b=O0jUxeP7WaCr7Ie2IK8/22Deopsuxvm27zw0me8r/9n2iTdyJ9SPFB4z 3YiGUK5E1ERQo0FArzMPyHqnTM46+Ca0m47OyVp+fVz5ym9FDixisJx4j d+IsiBkUg4u0/wRiK/H0wPHdHYw49oe2qyBdwDv0OzZha0MxftY5nr1dU iCjXgoKwgDGrOUuaavA0eAK8vm2KsqLde6LZUcnD6a9ZTDXHoSc9CkzKY oHVNpCDlLn6syJWB4aU8yFrrp9uxm9TTPc9MYQx/g+qEwuySraQFGAfg1 SyB+4d1eEds5nXItFh12By4mz1Y/dgKrUq5D6z0zwkpvD9TZvtl+kcHeH w==; IronPort-SDR: KoAwTB3paoivmfxqH9gQVk3qlUw62/68d7Bi9up/Z8+WykGTtll6JcXYadVWaO/+PAG+vWa67o 8guaMaTC+SGaejW5t87Yv56qsvqTGNxeQ7m0p+N0OwQmo4jGNanMzBTJEHFhmYgh27JkHbMQzL Cx0oHdtT2Sbx7azFYmjc62gazieksZsL1uSjfEkxaMAHf0kAcdyEIkSlCHtiPxDiF9y6tAd7Kk nBOXp65HrEYH7/pPzveb77O1BcAgkYbp1xd3s6rJXLfiKNtPLL+IS3AX7w8xxzRLwNj43q+Mhb mO4= X-IronPort-AV: E=Sophos;i="5.73,441,1583218800"; d="scan'208";a="81203092" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa1.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 27 May 2020 07:29:23 -0700 Received: from chn-vm-ex01.mchp-main.com (10.10.85.143) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Wed, 27 May 2020 07:29:23 -0700 Received: from soft-dev15.microsemi.net.microchip.com (10.10.115.15) by chn-vm-ex01.mchp-main.com (10.10.85.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5 via Frontend Transport; Wed, 27 May 2020 07:29:12 -0700 References: <20200513125532.24585-1-lars.povlsen@microchip.com> <20200513125532.24585-13-lars.povlsen@microchip.com> <159054818459.88029.10644772284176356883@swboyd.mtv.corp.google.com> From: Lars Povlsen To: Stephen Boyd List-Id: CC: Arnd Bergmann , Linus Walleij , SoC Team , Lars Povlsen , "Steen Hegelund" , Microchip Linux Driver Support , Olof Johansson , "Michael Turquette" , , , , , , Alexandre Belloni Subject: Re: [PATCH 12/14] clk: sparx5: Add Sparx5 SoC DPLL clock driver In-Reply-To: <159054818459.88029.10644772284176356883@swboyd.mtv.corp.google.com> Date: Wed, 27 May 2020 16:29:17 +0200 Message-ID: <87mu5tpi2q.fsf@soft-dev15.microsemi.net> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stephen Boyd writes: > Quoting Lars Povlsen (2020-05-13 05:55:30) >> diff --git a/drivers/clk/clk-sparx5.c b/drivers/clk/clk-sparx5.c >> new file mode 100644 >> index 0000000000000..685b3028a7071 >> --- /dev/null >> +++ b/drivers/clk/clk-sparx5.c >> @@ -0,0 +1,269 @@ >> +// SPDX-License-Identifier: GPL-2.0-or-later >> +/* >> + * Microchip Sparx5 SoC Clock driver. >> + * >> + * Copyright (c) 2019 Microchip Inc. >> + * >> + * Author: Lars Povlsen >> + */ >> + >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> + >> +#define PLL_DIV_MASK GENMASK(7, 0) >> +#define PLL_PRE_DIV_MASK GENMASK(10, 8) >> +#define PLL_PRE_DIV_SHIFT 8 >> +#define PLL_ROT_DIR BIT(11) >> +#define PLL_ROT_SEL_MASK GENMASK(13, 12) >> +#define PLL_ROT_SEL_SHIFT 12 >> +#define PLL_ROT_ENA BIT(14) >> +#define PLL_CLK_ENA BIT(15) >> + >> +#define MAX_SEL 4 >> +#define MAX_PRE BIT(3) >> + >> +#define KHZ 1000 >> +#define MHZ (KHZ*KHZ) > > I suspect (1000 * KHZ) would make more sense. > Fine. >> + >> +#define BASE_CLOCK (2500UL*MHZ) >> + >> +static u8 sel_rates[MAX_SEL] = { 0, 2*8, 2*4, 2*2 }; > > const? > Yes, sure. >> + >> +static const char *clk_names[N_CLOCKS] = { >> + "core", "ddr", "cpu2", "arm2", >> + "aux1", "aux2", "aux3", "aux4", >> + "synce", >> +}; >> + >> +struct s5_hw_clk { >> + struct clk_hw hw; >> + void __iomem *reg; >> + int index; >> +}; >> + >> +struct s5_clk_data { >> + void __iomem *base; >> + struct s5_hw_clk s5_hw[N_CLOCKS]; >> +}; >> + >> +struct pll_conf { >> + int freq; >> + u8 div; >> + bool rot_ena; >> + u8 rot_sel; >> + u8 rot_dir; >> + u8 pre_div; >> +}; >> + >> +#define to_clk_pll(hw) container_of(hw, struct s5_hw_clk, hw) >> + >> +unsigned long calc_freq(const struct pll_conf *pdata) >> +{ >> + unsigned long rate = BASE_CLOCK / pdata->div; >> + >> + if (pdata->rot_ena) { >> + unsigned long base = BASE_CLOCK / pdata->div; >> + int sign = pdata->rot_dir ? -1 : 1; >> + int divt = sel_rates[pdata->rot_sel] * (1 + pdata->pre_div); >> + int divb = divt + sign; >> + >> + rate = mult_frac(base, divt, divb); >> + rate = roundup(rate, 1000); >> + } >> + >> + return rate; >> +} >> + >> +static unsigned long clk_calc_params(unsigned long rate, >> + struct pll_conf *conf) >> +{ >> + memset(conf, 0, sizeof(*conf)); >> + >> + conf->div = DIV_ROUND_CLOSEST_ULL(BASE_CLOCK, rate); >> + >> + if (BASE_CLOCK % rate) { >> + struct pll_conf best; >> + ulong cur_offset, best_offset = rate; >> + int i, j; >> + >> + /* Enable fractional rotation */ >> + conf->rot_ena = true; >> + >> + if ((BASE_CLOCK / rate) != conf->div) { >> + /* Overshoot, adjust other direction */ >> + conf->rot_dir = 1; >> + } >> + >> + /* Brute force search over MAX_PRE * (MAX_SEL - 1) = 24 */ >> + for (i = 0; i < MAX_PRE; i++) { >> + conf->pre_div = i; >> + for (j = 1; j < MAX_SEL; j++) { >> + conf->rot_sel = j; >> + conf->freq = calc_freq(conf); >> + cur_offset = abs(rate - conf->freq); >> + if (cur_offset == 0) >> + /* Perfect fit */ >> + goto done; > > Why not 'break' and drop the label? > Its a dual loop. Anyway, I changed it to add "best_offset > 0" in the loop guards and drop "cur_offset == 0" as a special case, so no goto. >> + if (cur_offset < best_offset) { >> + /* Better fit found */ >> + best_offset = cur_offset; >> + best = *conf; >> + } >> + } >> + } >> + /* Best match */ >> + *conf = best; >> + } >> + >> +done: >> + return conf->freq; >> +} >> + >> +static int clk_pll_enable(struct clk_hw *hw) >> +{ >> + struct s5_hw_clk *pll = to_clk_pll(hw); >> + u32 val = readl(pll->reg); >> + >> + val |= PLL_CLK_ENA; >> + writel(val, pll->reg); >> + pr_debug("%s: Enable val %04x\n", clk_names[pll->index], val); >> + return 0; >> +} >> + >> +static void clk_pll_disable(struct clk_hw *hw) >> +{ >> + struct s5_hw_clk *pll = to_clk_pll(hw); >> + u32 val = readl(pll->reg); >> + >> + val &= ~PLL_CLK_ENA; >> + writel(val, pll->reg); >> + pr_debug("%s: Disable val %04x\n", clk_names[pll->index], val); > > Can we drop these pr_debug() prints? They're probably never going to be > used after developing this driver. > >> +} >> + >> +static int clk_pll_set_rate(struct clk_hw *hw, > > Please rename clk_pll to something less generic, like s5_pll or > something. > Yeah, I see that. I changed all generic symbols to use s5_ prefix where applicable. Also fixed non-static calc_freq() symbol. >> + unsigned long rate, >> + unsigned long parent_rate) >> +{ >> + struct s5_hw_clk *pll = to_clk_pll(hw); >> + struct pll_conf conf; >> + unsigned long eff_rate; >> + int ret = 0; >> + >> + eff_rate = clk_calc_params(rate, &conf); >> + if (eff_rate == rate) { >> + u32 val; >> + >> + val = readl(pll->reg) & PLL_CLK_ENA; >> + val |= PLL_DIV_MASK & conf.div; >> + if (conf.rot_ena) { >> + val |= (PLL_ROT_ENA | >> + (PLL_ROT_SEL_MASK & >> + (conf.rot_sel << PLL_ROT_SEL_SHIFT)) | >> + (PLL_PRE_DIV_MASK & >> + (conf.pre_div << PLL_PRE_DIV_SHIFT))); > > This can use the FIELD_GET and helpers? > Yes, makes sense. Done. >> + if (conf.rot_dir) >> + val |= PLL_ROT_DIR; >> + } >> + pr_debug("%s: Rate %ld >= 0x%04x\n", >> + clk_names[pll->index], rate, val); >> + writel(val, pll->reg); >> + } else { >> + pr_err("%s: freq unsupported: %ld paren %ld\n", >> + clk_names[pll->index], rate, parent_rate); >> + ret = -ENOTSUPP; > > I'd prefer we short circuit the function > > eff_rate = clk_calc_params(...); > if (eff_rate != rate) > return -ENOTSUPP; > > do the other things... > > This avoids lots of indentation. Ok, noted. > >> + } >> + >> + return ret; >> +} >> + >> +static unsigned long clk_pll_recalc_rate(struct clk_hw *hw, >> + unsigned long parent_rate) >> +{ >> + /* Don't care */ > > What does this mean? recalc_rate is supposed to tell us what rate has > been achieved for this clk. I added a proper implementation for this. > >> + return 0; >> +} >> + >> +static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate, >> + unsigned long *parent_rate) >> +{ >> + struct pll_conf conf; >> + unsigned long eff_rate; >> + >> + eff_rate = clk_calc_params(rate, &conf); >> + pr_debug("%s: Rate %ld rounded to %ld\n", __func__, rate, eff_rate); >> + >> + return eff_rate; >> +} >> + >> +static const struct clk_ops s5_pll_ops = { >> + .enable = clk_pll_enable, >> + .disable = clk_pll_disable, >> + .set_rate = clk_pll_set_rate, >> + .round_rate = clk_pll_round_rate, >> + .recalc_rate = clk_pll_recalc_rate, >> +}; >> + >> +static struct s5_clk_data *s5_clk_alloc(struct device_node *np) >> +{ >> + struct s5_clk_data *clk_data; >> + >> + clk_data = kzalloc(sizeof(*clk_data), GFP_KERNEL); >> + if (WARN_ON(!clk_data)) > > Drop the WARN_ON(), kzalloc() already prints a big stacktrace when it > fails. Yes. > >> + return NULL; >> + >> + clk_data->base = of_iomap(np, 0); >> + if (WARN_ON(!clk_data->base)) >> + return NULL; >> + >> + return clk_data; > > Just inline this function at the callsite please. > Yes. >> +} >> + >> +static struct clk_hw *s5_clk_hw_get(struct of_phandle_args *clkspec, void *data) >> +{ >> + struct s5_clk_data *pll_clk = data; >> + unsigned int idx = clkspec->args[0]; >> + >> + if (idx >= N_CLOCKS) { >> + pr_err("%s: invalid index %u\n", __func__, idx); >> + return ERR_PTR(-EINVAL); >> + } >> + >> + return &pll_clk->s5_hw[idx].hw; >> +} >> + >> +static void __init s5_pll_init(struct device_node *np) >> +{ >> + int i, ret; >> + struct s5_clk_data *pll_clk; >> + struct clk_init_data init = { 0 }; > > Just do init = { } so that 0 doesn't trip up sparse. I'm not sure what you mean by "trip up sparse", but its changed now. > >> + >> + pll_clk = s5_clk_alloc(np); >> + if (!pll_clk) >> + return; >> + >> + init.ops = &s5_pll_ops; >> + init.parent_names = NULL; >> + init.num_parents = 0; > > Drop these last two lines if there aren't any parents. > OK. >> + >> + for (i = 0; i < N_CLOCKS; i++) { >> + struct s5_hw_clk *s5_hw = &pll_clk->s5_hw[i]; >> + >> + init.name = clk_names[i]; >> + s5_hw->index = i; >> + s5_hw->reg = pll_clk->base + (i * sizeof(u32)); >> + s5_hw->hw.init = &init; >> + ret = of_clk_hw_register(np, &s5_hw->hw); >> + if (ret) { >> + pr_err("failed to register %s clock\n", init.name); >> + return; >> + } >> + } >> + >> + of_clk_add_hw_provider(np, s5_clk_hw_get, pll_clk); >> +} >> +CLK_OF_DECLARE_DRIVER(microchip_s5, "microchip,sparx5-dpll", s5_pll_init); > > Why DECLARE_DRIVER? Please add a comment indicating the other driver > that is supposed to probe against this node. And is there any reason > this can't be a platform driver? That is preferred over > CLK_OF_DECLARE*() usage. I will change it to a platform driver. Thank you very much for your comments, they are highly appreciated. ---Lars -- Lars Povlsen, Microchip