linux-kernel - Re: [PATCH v1 08/12] clk: imx: Add initial support for i.MXRT1170 clock driver

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Date:   Sat, 23 Apr 2022 23:53:19 -0400
From:   Jesse Taube <mr.bossman075@...il.com>
To:     Stephen Boyd <sboyd@...nel.org>, linux-imx@....com
Cc:     robh+dt@...nel.org, mturquette@...libre.com, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        aisheng.dong@....com, stefan@...er.ch, linus.walleij@...aro.org,
        daniel.lezcano@...aro.org, tglx@...utronix.de, arnd@...db.de,
        olof@...om.net, soc@...nel.org, linux@...linux.org.uk,
        abel.vesa@....com, dev@...xeye.de, marcel.ziswiler@...adex.com,
        tharvey@...eworks.com, leoyang.li@....com,
        sebastian.reichel@...labora.com, cniedermaier@...electronics.com,
        clin@...e.com, giulio.benetti@...ettiengineering.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-gpio@...r.kernel.org
Subject: Re: [PATCH v1 08/12] clk: imx: Add initial support for i.MXRT1170
 clock driver



On 4/22/22 23:03, Stephen Boyd wrote:
> Quoting Jesse Taube (2022-03-26 07:43:09)
>> diff --git a/drivers/clk/imx/clk-imxrt1170.c b/drivers/clk/imx/clk-imxrt1170.c
>> new file mode 100644
>> index 000000000000..041aea3d4b02
>> --- /dev/null
>> +++ b/drivers/clk/imx/clk-imxrt1170.c
>> @@ -0,0 +1,391 @@
>> +// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
>> +/*
>> + * Copyright (C) 2022
>> + * Author(s):
>> + * Jesse Taube <Mr.Bossman075@...il.com>
>> + */
>> +#include <linux/clk.h>
>> +#include <linux/of_address.h>
> 
> Is this include used?
> 
Yes `of_iomap`
>> +#include <linux/of_irq.h>
> 
> Is this include used?
> 
No, but includes
#include <linux/slab.h>
for `kzalloc`
>> +#include <linux/platform_device.h>
> 
> Need to include clk-provider.h
> 
>> +#include <dt-bindings/clock/imxrt1170-clock.h>
>> +
>> +#include "clk.h"
>> +
>> +#define CLOCK_MUX_DEFAULT "rcosc48M_div2", "osc", "rcosc400M", "rcosc16M"
>> +
>> +#define LPCG_GATE(gate) (0x6000 + (gate * 0x20))
>> +
>> +#define DEF_CLOCK(flags, macro, name) \
>> +do { \
>> +       hws[macro##_SEL] = imx_clk_hw_mux(#name"_sel", ccm_base + (name * 0x80), \
>> +               8, 3, root_clocks[name], 8); \
>> +       hws[macro##_GATE] = imx_clk_hw_gate_dis_flags(#name"_gate", #name"_sel", \
>> +               ccm_base + (name * 0x80), 24, flags); \
>> +       hws[macro] = imx_clk_hw_divider(#name, #name"_gate", ccm_base + (name * 0x80), 0, 8); \
>> +} while (0)
>> +
>> +enum root_clock_names {
>> +       m7,             /* root clock m7. */
> 
> Is the comment adding any value? It has the enum name after "root clock"
> and the enum is "root_clock_names" so it looks very obvious.
> 
>> +       m4,             /* root clock m4. */
>> +       bus,            /* root clock bus. */
>> +       bus_lpsr,       /* root clock bus lpsr. */
> [...]
>> +       end,            /* root clock end. */
>> +};
>> +
>> +static const char * const root_clocks[79][8] = {
>> +       {CLOCK_MUX_DEFAULT, "pll_arm", "pll1_sys", "pll3_sys", "pll_video"},
> 
> Space after { and before }
> 
>> +       {CLOCK_MUX_DEFAULT, "pll3_pfd3", "pll3_sys", "pll2_sys", "pll1_div5"},
>> +       {CLOCK_MUX_DEFAULT, "pll3_sys", "pll1_div5", "pll2_sys", "pll2_pfd3"},
> [...]
>> +       {CLOCK_MUX_DEFAULT, "pll2_pfd3", "rcosc48M", "pll3_pfd1", "pll_audio"}
>> +};
>> +
>> +static const char * const pll_arm_mux[] = {"pll_arm_pre", "osc"};
>> +static const char * const pll3_mux[] = {"pll3_pre", "osc"};
>> +static const char * const pll2_mux[] = {"pll2_pre", "osc"};
>> +
>> +static const struct clk_div_table post_div_table[] = {
>> +       { .val = 3, .div = 1, },
>> +       { .val = 2, .div = 8, },
>> +       { .val = 1, .div = 4, },
>> +       { .val = 0, .div = 2, },
>> +       { }
>> +};
>> +
>> +static struct clk_hw **hws;
>> +static struct clk_hw_onecell_data *clk_hw_data;
> 
> Do either of these need to be static global variables? They could be
> local function pointers allocated on the heap (like they already are).
> 
>> +
>> +static int imxrt1170_clocks_probe(struct platform_device *pdev)
>> +{
> [...]
>> +       hws[IMXRT1170_CLK_PLL2_PFD3] = imx_clk_hw_pfd("pll2_pfd3", "pll2_sys", pll_base + 0x270, 3);
>> +
>> +       /* CCM clocks */
>> +       ccm_base = devm_platform_ioremap_resource(pdev, 0);
>> +       if (WARN_ON(IS_ERR(ccm_base)))
>> +               return PTR_ERR(ccm_base);
>> +
>> +       DEF_CLOCK(CLK_IS_CRITICAL, IMXRT1170_CLK_M7, m7);
> 
> Don't have macros do things to variables that are in global scope. It
> makes things very non-obvious. Instead, pass hw to the macro, or better
> yet make a static inline function and let the compiler decide to inline
> it or not.
> 
>> +       DEF_CLOCK(CLK_IS_CRITICAL, IMXRT1170_CLK_M4, m4);
> [...]
>> +       DEF_CLOCK(0, IMXRT1170_CLK_CSI2_UI, csi2_ui);
>> +       DEF_CLOCK(0, IMXRT1170_CLK_CSI, csi);
>> +       DEF_CLOCK(0, IMXRT1170_CLK_CKO1, cko1);
>> +       DEF_CLOCK(0, IMXRT1170_CLK_CKO2, cko2);
>> +
>> +       hws[IMXRT1170_CLK_USB] = imx_clk_hw_gate("usb", "bus", ccm_base + LPCG_GATE(115), 0);
>> +
>> +       clk_set_rate(hws[IMXRT1170_CLK_PLL_ARM]->clk, 90000000);
> 
> Use assigned-clock-rates?
> 
>> +
>> +       imx_check_clk_hws(hws, IMXRT1170_CLK_END);