Subject: [PATCH v3 03/10] clk: qcom: Add CPU clock driver for msm8996

From: [email-masked] (ilialin at codeaurora.org)
Date: Tue, 20 Mar 2018 16:18:57 +0200

> -----Original Message-----
> From: Stephen Boyd <[email-masked]>
> Sent: Monday, March 19, 2018 19:37
> To: Ilia Lin <[email-masked]>; linux-arm-kernel at lists.infradead.org;
> linux-arm-msm at vger.kernel.org; linux-clk at vger.kernel.org;
> sboyd at codeaurora.org
> Cc: mark.rutland at arm.com; devicetree at vger.kernel.org;
> rnayak at codeaurora.org; robh at kernel.org; will.deacon at arm.com;
> amit.kucheria at linaro.org; tfinkel at codeaurora.org; ilialin at codeaurora.org;
> nicolas.dechesne at linaro.org; celster at codeaurora.org
> Subject: Re: [PATCH v3 03/10] clk: qcom: Add CPU clock driver for msm8996
> 
> Quoting Ilia Lin (2018-02-14 05:59:45)
> > From: Rajendra Nayak <[email-masked]>
> >
> > Each of the CPU clusters (Power and Perf) on msm8996 are clocked via 2
> > PLLs, a primary and alternate. There are also
> > 2 Mux'es, a primary and secondary all connected together as shown
> > below
> >
> >                              +-------+
> >               XO             |       |
> >           +------------------>0      |
> >                              |       |
> >                    PLL/2     | SMUX  +----+
> >                      +------->1      |    |
> >                      |       |       |    |
> >                      |       +-------+    |    +-------+
> >                      |                    +---->0      |
> >                      |                         |       |
> > +---------------+    |             +----------->1      | CPU clk
> > |Primary PLL    +----+ PLL_EARLY   |           |       +------>
> > |               +------+-----------+    +------>2 PMUX |
> > +---------------+      |                |      |       |
> >                        |   +------+     |   +-->3      |
> >                        +--^+  ACD +-----+   |  +-------+
> > +---------------+          +------+         |
> > |Alt PLL        |                           |
> > |               +---------------------------+
> > +---------------+         PLL_EARLY
> 
> Thanks for the diagram. Please also put it at the top of the driver file.

Will be added in the next spin.

> 
> >
> > The primary PLL is what drives the CPU clk, except for times when we
> > are reprogramming the PLL itself (for rate changes) when we
> > temporarily switch to an alternate PLL. A subsequent patch adds
> > support to switch between primary and alternate PLL during rate
> > changes.
> >
> > The primary PLL operates on a single VCO range, between 600Mhz and
> > 3Ghz. However the CPUs do support OPPs with frequencies between
> 300Mhz
> > and 600Mhz. In order to support running the CPUs at those frequencies
> > we end up having to lock the PLL at twice the rate and drive the CPU
> > clk via the PLL/2 output and SMUX.
> >
> > So for frequencies above 600Mhz we follow the following path  Primary
> > PLL --> PLL_EARLY --> PMUX(1) --> CPU clk and for frequencies between
> > 300Mhz and 600Mhz we follow
> 
> Capitalize 'h' in units please.

OK

> 
> >  Primary PLL --> PLL/2 --> SMUX(1) --> PMUX(0) --> CPU clk Support for
> > this is added in a subsequent patch as well.
> >
> > ACD stands for Adaptive Clock Distribution and is used to detect
> > voltage droops. We do not add support for ACD as yet.
> > This can be added at a later point as needed.
> >
> > Signed-off-by: Rajendra Nayak <[email-masked]>
> > Signed-off-by: Ilia Lin <[email-masked]>
> > ---
> >  drivers/clk/qcom/Kconfig        |   8 +
> >  drivers/clk/qcom/Makefile       |   1 +
> >  drivers/clk/qcom/clk-cpu-8996.c | 409
> > ++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 418 insertions(+)
> >  create mode 100644 drivers/clk/qcom/clk-cpu-8996.c
> >
> > diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig index
> > fbf4532..3274877 100644
> > --- a/drivers/clk/qcom/Kconfig
> > +++ b/drivers/clk/qcom/Kconfig
> > @@ -226,3 +226,11 @@ config SPMI_PMIC_CLKDIV
> >           Technologies, Inc. SPMI PMIC. It configures the frequency of
> >           clkdiv outputs of the PMIC. These clocks are typically wired
> >           through alternate functions on GPIO pins.
> > +
> > +config MSM_APCC_8996
> > +       tristate "MSM8996 CPU Clock Controller"
> > +       depends on COMMON_CLK_QCOM
> > +       help
> > +         Support for the CPU clock controller on msm8996 devices.
> > +         Say Y if you want to support CPU clock scaling using CPUfreq
> > +         drivers for dyanmic power management.
> 
> Sort?

Will be changed in the next spin.

> 
> > diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
> > index 230332c..57b38ba 100644
> > --- a/drivers/clk/qcom/Makefile
> > +++ b/drivers/clk/qcom/Makefile
> > @@ -33,6 +33,7 @@ obj-$(CONFIG_MSM_LCC_8960) += lcc-msm8960.o
> >  obj-$(CONFIG_MSM_MMCC_8960) += mmcc-msm8960.o
> >  obj-$(CONFIG_MSM_MMCC_8974) += mmcc-msm8974.o
> >  obj-$(CONFIG_MSM_MMCC_8996) += mmcc-msm8996.o
> > +obj-$(CONFIG_MSM_APCC_8996) += clk-cpu-8996.o
> 
> This doesn't look sorted.

Will be changed in the next spin.

> 
> >  obj-$(CONFIG_QCOM_A53PLL) += a53-pll.o
> >  obj-$(CONFIG_QCOM_CLK_APCS_MSM8916) += apcs-msm8916.o
> >  obj-$(CONFIG_QCOM_CLK_RPM) += clk-rpm.o diff --git
> > a/drivers/clk/qcom/clk-cpu-8996.c b/drivers/clk/qcom/clk-cpu-8996.c
> > new file mode 100644 index 0000000..42489f1
> > --- /dev/null
> > +++ b/drivers/clk/qcom/clk-cpu-8996.c
> > @@ -0,0 +1,409 @@
> > +/*
> > + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > +modify
> > + * it under the terms of the GNU General Public License version 2 and
> > + * only version 2 as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
> 
> Can we get the SPDX tags here please?

Will be changed in the next spin.

> 
> > +
> > +#include <linux/clk.h>
> 
> clk-provider.h?
> 
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +
> > +#include "clk-alpha-pll.h"
> 
> #include "clk-regmap.h"
> 
> > +
> > +#define VCO(a, b, c) { \
> > +       .val = a,\
> > +       .min_freq = b,\
> > +       .max_freq = c,\
> > +}
> 
> Can this define go into whatever PLL header file defines the struct?

Will be changed in the next spin.

> 
> > +
> > +#define DIV_2_INDEX            0
> > +#define PLL_INDEX              1
> > +#define ACD_INDEX              2
> > +#define ALT_INDEX              3
> > +
> > +static const u8 prim_pll_regs[PLL_OFF_MAX_REGS] = {
> > +       [PLL_OFF_L_VAL] = 0x04,
> > +       [PLL_OFF_ALPHA_VAL] = 0x08,
> > +       [PLL_OFF_USER_CTL] = 0x10,
> > +       [PLL_OFF_CONFIG_CTL] = 0x18,
> > +       [PLL_OFF_CONFIG_CTL_U] = 0x1C,
> 
> Please use lowercase hex throughout. Consistency is key!

Will be changed in the next spin.

> 
> > +       [PLL_OFF_TEST_CTL] = 0x20,
> > +       [PLL_OFF_TEST_CTL_U] = 0x24,
> > +       [PLL_OFF_STATUS] = 0x28,
> > +};
> > +
> > +static const u8 alt_pll_regs[PLL_OFF_MAX_REGS] = {
> > +       [PLL_OFF_L_VAL] = 0x04,
> > +       [PLL_OFF_ALPHA_VAL] = 0x08,
> > +       [PLL_OFF_ALPHA_VAL_U] = 0x0c,
> > +       [PLL_OFF_USER_CTL] = 0x10,
> > +       [PLL_OFF_USER_CTL_U] = 0x14,
> > +       [PLL_OFF_CONFIG_CTL] = 0x18,
> > +       [PLL_OFF_TEST_CTL] = 0x20,
> > +       [PLL_OFF_TEST_CTL_U] = 0x24,
> > +       [PLL_OFF_STATUS] = 0x28,
> > +};
> > +
> > +/* PLLs */
> > +
> > +static const struct alpha_pll_config hfpll_config = {
> > +       .l = 60,
> > +       .config_ctl_val = 0x200d4828,
> > +       .config_ctl_hi_val = 0x006,
> > +       .pre_div_mask = BIT(12),
> > +       .post_div_mask = 0x3 << 8,
> > +       .main_output_mask = BIT(0),
> > +       .early_output_mask = BIT(3),
> > +};
> > +
> > +static struct clk_alpha_pll perfcl_pll = {
> > +       .offset = 0x80000,
> > +       .regs = prim_pll_regs,
> > +       .flags = SUPPORTS_DYNAMIC_UPDATE | SUPPORTS_FSM_MODE,
> > +       .clkr.hw.init = &(struct clk_init_data){
> > +               .name = "perfcl_pll",
> > +               .parent_names = (const char *[]){ "xo" },
> > +               .num_parents = 1,
> > +               .ops = &clk_alpha_pll_huayra_ops,
> > +       },
> > +};
> > +
> > +static struct clk_alpha_pll pwrcl_pll = {
> > +       .offset = 0x0,
> > +       .regs = prim_pll_regs,
> > +       .flags = SUPPORTS_DYNAMIC_UPDATE | SUPPORTS_FSM_MODE,
> > +       .clkr.hw.init = &(struct clk_init_data){
> > +               .name = "pwrcl_pll",
> > +               .parent_names = (const char *[]){ "xo" },
> > +               .num_parents = 1,
> > +               .ops = &clk_alpha_pll_huayra_ops,
> > +       },
> > +};
> > +
> > +static const struct pll_vco alt_pll_vco_modes[] = {
> > +       VCO(3,  250000000,  500000000),
> > +       VCO(2,  500000000,  750000000),
> > +       VCO(1,  750000000, 1000000000),
> > +       VCO(0, 1000000000, 2150400000), };
> > +
> > +static const struct alpha_pll_config altpll_config = {
> > +       .l = 16,
> > +       .vco_val = 0x3 << 20,
> > +       .vco_mask = 0x3 << 20,
> > +       .config_ctl_val = 0x4001051b,
> > +       .post_div_mask = 0x3 << 8,
> > +       .post_div_val = 0x1,
> > +       .main_output_mask = BIT(0),
> > +       .early_output_mask = BIT(3),
> > +};
> > +
> > +static struct clk_alpha_pll perfcl_alt_pll = {
> > +       .offset = 0x80100,
> > +       .regs = alt_pll_regs,
> > +       .vco_table = alt_pll_vco_modes,
> > +       .num_vco = ARRAY_SIZE(alt_pll_vco_modes),
> > +       .flags = SUPPORTS_OFFLINE_REQ | SUPPORTS_FSM_MODE,
> > +       .clkr.hw.init = &(struct clk_init_data) {
> > +               .name = "perfcl_alt_pll",
> > +               .parent_names = (const char *[]){ "xo" },
> > +               .num_parents = 1,
> > +               .ops = &clk_alpha_pll_hwfsm_ops,
> > +       },
> > +};
> > +
> > +static struct clk_alpha_pll pwrcl_alt_pll = {
> > +       .offset = 0x100,
> > +       .regs = alt_pll_regs,
> > +       .vco_table = alt_pll_vco_modes,
> > +       .num_vco = ARRAY_SIZE(alt_pll_vco_modes),
> > +       .flags = SUPPORTS_OFFLINE_REQ | SUPPORTS_FSM_MODE,
> > +       .clkr.hw.init = &(struct clk_init_data) {
> > +               .name = "pwrcl_alt_pll",
> > +               .parent_names = (const char *[]){ "xo" },
> > +               .num_parents = 1,
> > +               .ops = &clk_alpha_pll_hwfsm_ops,
> > +       },
> > +};
> > +
> > +/* Mux'es */
> > +
> > +struct clk_cpu_8996_mux {
> > +       u32     reg;
> > +       u32     shift;
> 
> u8 shift?

Will be changed in the next spin.

> > +       u32     width;
> u8 width?

Will be changed in the next spin.

> 
> > +       struct clk_hw   *pll;
> > +       struct clk_regmap clkr;
> > +};
> > +
> > +static inline
> > +struct clk_cpu_8996_mux *to_clk_cpu_8996_mux_hw(struct clk_hw
> *hw) {
> > +       return container_of(to_clk_regmap(hw), struct
> > +clk_cpu_8996_mux, clkr); }
> > +
> > +static u8 clk_cpu_8996_mux_get_parent(struct clk_hw *hw) {
> > +       unsigned int val;
> > +       struct clk_regmap *clkr = to_clk_regmap(hw);
> > +       struct clk_cpu_8996_mux *cpuclk = to_clk_cpu_8996_mux_hw(hw);
> > +       unsigned int mask = GENMASK(cpuclk->width - 1, 0);
> > +
> > +       regmap_read(clkr->regmap, cpuclk->reg, &val);
> > +
> > +       val >>= cpuclk->shift;
> > +       val &= mask;
> > +
> > +       return val;
> 
> return val & mask;

struct clk_cpu_8996_mux *

> 
> > +}
> > +
> > +static int clk_cpu_8996_mux_set_parent(struct clk_hw *hw, u8 index) {
> > +       unsigned int val;
> 
> u32 val?

Will be changed in the next spin.

> 
> > +       struct clk_regmap *clkr = to_clk_regmap(hw);
> > +       struct clk_cpu_8996_mux *cpuclk = to_clk_cpu_8996_mux_hw(hw);
> > +       unsigned int mask = GENMASK(cpuclk->width + cpuclk->shift - 1,
> > +                                   cpuclk->shift);
> > +
> > +       val = index;
> > +       val <<= cpuclk->shift;
> > +
> > +       return regmap_update_bits(clkr->regmap, cpuclk->reg, mask,
> > +val); }
> > +
> > +static int
> > +clk_cpu_8996_mux_determine_rate(struct clk_hw *hw, struct
> > +clk_rate_request *req) {
> > +       struct clk_cpu_8996_mux *cpuclk = to_clk_cpu_8996_mux_hw(hw);
> > +       struct clk_hw *parent = cpuclk->pll;
> > +
> > +       if (!cpuclk->pll)
> > +               return -EINVAL;
> 
> Does this happen?

On successful probe it shouldn't. May I omit pointer checks in this case? Future maintenance ma y change the flow.

> 
> > +
> > +       req->best_parent_rate = clk_hw_round_rate(parent, req->rate);
> > +       req->best_parent_hw = parent;
> 
> Is the parent index always the same? Perhaps just call
> clk_hw_get_parent_by_index() then instead of adding a pointer to the
> clk_cpu_8996_mux.
> 
> > +
> > +       return 0;
> > +}
> > +
> > +const struct clk_ops clk_cpu_8996_mux_ops = {
> > +       .set_parent = clk_cpu_8996_mux_set_parent,
> > +       .get_parent = clk_cpu_8996_mux_get_parent,
> > +       .determine_rate = clk_cpu_8996_mux_determine_rate, };
> [...]
> > +
> > +static struct clk_cpu_8996_mux pwrcl_pmux = {
> > +       .reg = 0x40,
> > +       .shift = 0,
> > +       .width = 2,
> > +       .pll = &pwrcl_pll.clkr.hw,
> > +       .clkr.hw.init = &(struct clk_init_data) {
> > +               .name = "pwrcl_pmux",
> > +               .parent_names = (const char *[]){
> > +                       "pwrcl_smux",
> > +                       "pwrcl_pll",
> > +                       "pwrcl_pll_acd",
> > +                       "pwrcl_alt_pll",
> > +               },
> > +               .num_parents = 4,
> > +               .ops = &clk_cpu_8996_mux_ops,
> > +               .flags = CLK_SET_RATE_PARENT | CLK_IS_CRITICAL,
> > +       },
> > +};
> > +
> > +static struct clk_cpu_8996_mux perfcl_pmux = {
> > +       .reg = 0x80040,
> > +       .shift = 0,
> > +       .width = 2,
> > +       .pll = &perfcl_pll.clkr.hw,
> > +       .clkr.hw.init = &(struct clk_init_data) {
> > +               .name = "perfcl_pmux",
> > +               .parent_names = (const char *[]){
> > +                       "perfcl_smux",
> > +                       "perfcl_pll",
> > +                       "perfcl_pll_acd",
> > +                       "perfcl_alt_pll",
> > +               },
> > +               .num_parents = 4,
> > +               .ops = &clk_cpu_8996_mux_ops,
> > +               .flags = CLK_SET_RATE_PARENT | CLK_IS_CRITICAL,
> 
> Not sure CLK_IS_CRITICAL is the right mode. Perhaps CLK_IGNORE_UNUSED
> for now? We don't want to force XO to stay on forever here.

Have to unit test this.

> 
> > +       },
> > +};
> > +
> > +static const struct regmap_config cpu_msm8996_regmap_config = {
> > +       .reg_bits               = 32,
> > +       .reg_stride             = 4,
> > +       .val_bits               = 32,
> > +       .max_register           = 0x80210,
> > +       .fast_io                = true,
> > +       .val_format_endian      = REGMAP_ENDIAN_LITTLE,
> > +};
> > +
> > +static const struct of_device_id match_table[] = {
> 
> Move this next to driver structure and give it a more specific name.

Will be changed in the next spin.

> 
> > +       { .compatible = "qcom-msm8996-apcc" },
> 
> Bad compatible? Should be qcom,msm8996-apcc?

The naming is per Rob Herring's requirement.

> 
> > +       {}
> > +};
> > +
> > +struct clk_regmap *clks[] = {
> > +       /* PLLs */
> > +       &perfcl_pll.clkr,
> > +       &pwrcl_pll.clkr,
> > +       &perfcl_alt_pll.clkr,
> > +       &pwrcl_alt_pll.clkr,
> > +       /* MUXs */
> > +       &perfcl_smux.clkr,
> > +       &pwrcl_smux.clkr,
> > +       &perfcl_pmux.clkr,
> > +       &pwrcl_pmux.clkr,
> 
> Please drop useless comments inside this array.

Will be changed in the next spin.

> 
> > +};
> > +
> > +struct clk_hw_clks {
> > +       unsigned int num;
> > +       struct clk_hw *hws[];
> > +};
> 
> Please just NULL terminate the list of clk_hw pointers, or keep the size
> around instead.

Will be changed in the next spin.

> 
> > +
> > +static int
> > +qcom_cpu_clk_msm8996_register_clks(struct device *dev, struct
> clk_hw_clks *hws,
> > +                                  struct regmap *regmap) {
> > +       int i, ret;
> > +
> > +       hws->hws[0] = clk_hw_register_fixed_factor(dev, "perfcl_pll_main",
> > +                                                  "perfcl_pll",
> > +                                                  CLK_SET_RATE_PARENT, 1, 2);
> > +       perfcl_smux.pll = hws->hws[0];
> > +
> > +       hws->hws[1] = clk_hw_register_fixed_factor(dev, "pwrcl_pll_main",
> > +                                                  "pwrcl_pll",
> > +                                                  CLK_SET_RATE_PARENT, 1, 2);
> > +       pwrcl_smux.pll = hws->hws[1];
> > +
> > +       hws->num = 2;
> 
> Maybe just open code the fixed factor clk registration? Then the
> devm_clk_hw_register() function can be used on those static structs to make
> removal simpler.

I will check this.

> 
> > +
> > +       for (i = 0; i < ARRAY_SIZE(clks); i++) {
> > +               ret = devm_clk_register_regmap(dev, clks[i]);
> > +               if (ret)
> > +                       return ret;
> > +       }
> > +
> > +       clk_alpha_pll_configure(&perfcl_pll, regmap, &hfpll_config);
> > +       clk_alpha_pll_configure(&pwrcl_pll, regmap, &hfpll_config);
> > +       clk_alpha_pll_configure(&perfcl_alt_pll, regmap, &altpll_config);
> > +       clk_alpha_pll_configure(&pwrcl_alt_pll, regmap,
> > + &altpll_config);
> > +
> > +       return ret;
> > +}
> > +
> > +static int qcom_cpu_clk_msm8996_driver_probe(struct platform_device
> > +*pdev) {
> > +       int ret;
> > +       void __iomem *base;
> > +       struct resource *res;
> > +       struct regmap *regmap_cpu;
> 
> Just call it regmap please.

Will be changed in the next spin.

> 
> > +       struct clk_hw_clks *hws;
> > +       struct clk_hw_onecell_data *data;
> > +       struct device *dev = &pdev->dev;
> > +       struct device_node *node = dev->of_node;
> > +
> > +       data = devm_kzalloc(dev, sizeof(*data) + 2 * sizeof(struct clk_hw *),
> > +                           GFP_KERNEL);
> > +       if (!data)
> > +               return -ENOMEM;
> > +
> > +       hws = devm_kzalloc(dev, sizeof(*hws) + 2 * sizeof(struct clk_hw *),
> > +                          GFP_KERNEL);
> > +       if (!hws)
> > +               return -ENOMEM;
> > +
> > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       base = devm_ioremap_resource(dev, res);
> > +       if (IS_ERR(base))
> > +               return PTR_ERR(base);
> > +
> > +       regmap_cpu = devm_regmap_init_mmio(dev, base,
> > +                                          &cpu_msm8996_regmap_config);
> > +       if (IS_ERR(regmap_cpu))
> > +               return PTR_ERR(regmap_cpu);
> > +
> > +       ret = qcom_cpu_clk_msm8996_register_clks(dev, hws, regmap_cpu);
> > +       if (ret)
> > +               return ret;
> > +
> > +       data->hws[0] = &pwrcl_pmux.clkr.hw;
> > +       data->hws[1] = &perfcl_pmux.clkr.hw;
> > +
> > +       data->num = 2;
> > +
> > +       platform_set_drvdata(pdev, hws);
> > +
> > +       return of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
> > +data); }
> > +
> > +static int qcom_cpu_clk_msm8996_driver_remove(struct
> platform_device
> > +*pdev) {
> > +       int i;
> > +       struct device *dev = &pdev->dev;
> > +       struct clk_hw_clks *hws = platform_get_drvdata(pdev);
> > +
> > +       for (i = 0; i < hws->num; i++)
> > +               clk_hw_unregister_fixed_rate(hws->hws[i]);
> > +
> > +       of_clk_del_provider(dev->of_node);
> 
> Use devm_of_clk_add_hw_provider() instead.

Will be changed in the next spin.

> 
> > +
> > +       return 0;
> > +}
> > +
> > +static struct platform_driver qcom_cpu_clk_msm8996_driver = {
> > +       .probe = qcom_cpu_clk_msm8996_driver_probe,
> > +       .remove = qcom_cpu_clk_msm8996_driver_remove,
> > +       .driver = {
> > +               .name = "qcom-msm8996-apcc",
> > +               .of_match_table = match_table,
> > +       },
> > +};
> > +
> > +module_platform_driver(qcom_cpu_clk_msm8996_driver);
> > +
> > +MODULE_ALIAS("platform:msm8996-apcc");
> > +MODULE_DESCRIPTION("QCOM MSM8996 CPU clock Driver");
> 
> Not sure why Driver is capitalized and clock is not.

Will be changed in the next spin.