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SubjectRe: [RFC PATCH v3 2/2] drivers: mfd: vexpress: add Serial Power Controller (SPC) support
Hi Olof,

thank you very much for having a look.

On Thu, Jun 13, 2013 at 11:52:33PM +0100, Olof Johansson wrote:
> Hi,
>
> Overall this driver looks like it just needs more cooking
> time. It's... gritty. Complicated when it should be simple and
> layered. Naming is nonobvious, and overall it's hard to glance at a
> function and say "ah, it does <x>".

It is hard to make it clear too, and I am not on the defensive, it is
not a standard component following a standard interface, but point taken
I will do my best to improve it according to your reviews.

> I think some of this might be because of naming conventions. Lots of long
> prefixes, subsystem indirection, etc. I wish I had a straight answer to
> what would make it better, but just more overall polish.
>
> So, I have a bunch of comments below. Most of these are related to
> readability, which is one of the most important things of new code
> these days.
>
> Please find a shorter suitable prefix than vexpress_spc_.* too, it's
> way too long.

Ok.

> On Thu, Jun 06, 2013 at 10:59:23AM +0100, Lorenzo Pieralisi wrote:
> > The TC2 versatile express core tile integrates a logic block that provides the
> > interface between the dual cluster test-chip and the M3 microcontroller that
> > carries out power management. The logic block, called Serial Power Controller
> > (SPC), contains several memory mapped registers to control among other things
> > low-power states, operating points and reset control.
> >
> > This patch provides a driver that enables run-time control of features
> > implemented by the SPC control logic.
> >
> > The driver also provides a bridge interface through the vexpress config
> > infrastructure. Operations allowing to read/write operating points are
> > made to go via the same interface as configuration transactions so that
> > all requests to M3 are serialized.
> >
> > Device tree bindings documentation for the SPC component is provided with
> > the patchset.
> >
> > Cc: Samuel Ortiz <sameo@linux.intel.com>
> > Cc: Pawel Moll <pawel.moll@arm.com>
> > Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
> > Cc: Amit Kucheria <amit.kucheria@linaro.org>
> > Cc: Jon Medhurst <tixy@linaro.org>
> > Signed-off-by: Achin Gupta <achin.gupta@arm.com>
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > Signed-off-by: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@arm.com>
> > Reviewed-by: Nicolas Pitre <nico@linaro.org>
> > ---
> > Documentation/devicetree/bindings/mfd/vexpress-spc.txt | 35 +
> > drivers/mfd/Kconfig | 7 +
> > drivers/mfd/Makefile | 1 +
> > drivers/mfd/vexpress-spc.c | 633 ++++++++++
> > include/linux/vexpress.h | 43 +
> > 5 files changed, 719 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/mfd/vexpress-spc.txt b/Documentation/devicetree/bindings/mfd/vexpress-spc.txt
> > new file mode 100644
> > index 0000000..1d71dc2
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mfd/vexpress-spc.txt
> > @@ -0,0 +1,35 @@
> > +* ARM Versatile Express Serial Power Controller device tree bindings
> > +
> > +Latest ARM development boards implement a power management interface (serial
> > +power controller - SPC) that is capable of managing power/voltage and
> > +operating point transitions, through memory mapped registers interface.
> > +
> > +On testchips like TC2 it also provides a configuration interface that can
> > +be used to read/write values which cannot be read/written through simple
> > +memory mapped reads/writes.
>
> A configuration interface for what? Just having it as a PMIC doesn't warrant it
> being an MFD, really.

Ok, description added.

> > +- spc node
> > +
> > + - compatible:
> > + Usage: required
> > + Value type: <stringlist>
> > + Definition: must be
> > + "arm,vexpress-spc,v2p-ca15_a7","arm,vexpress-spc"
> > + - reg:
> > + Usage: required
> > + Value type: <prop-encode-array>
> > + Definition: A standard property that specifies the base address
> > + and the size of the SPC address space
> > + - interrupts:
> > + Usage: required
> > + Value type: <prop-encoded-array>
> > + Definition: SPC interrupt configuration. A standard property
> > + that follows ePAPR interrupts specifications
> > +
> > +Example:
> > +
> > +spc: spc@7fff0000 {
> > + compatible = "arm,vexpress-spc,v2p-ca15_a7","arm,vexpress-spc";
>
> Nit: space after comma between strings.
>
> > + reg = <0 0x7FFF0000 0 0x1000>;
>
> #size-cells 2 on the parent bus? That's somewhat unusual. We tend to prefer
> lowercase hex.
>

Ok on both counts.

> > + interrupts = <0 95 4>;
> > +};
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index d54e985..391eda1 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -1148,3 +1148,10 @@ config VEXPRESS_CONFIG
> > help
> > Platform configuration infrastructure for the ARM Ltd.
> > Versatile Express.
> > +
> > +config VEXPRESS_SPC
> > + bool "Versatile Express SPC driver support"
> > + depends on ARM
> > + depends on VEXPRESS_CONFIG
> > + help
> > + Serial Power Controller driver for ARM Ltd. test chips.
>
> One more line as to what conditions you'd like to have this enabled for would
> be good.

Done.

> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index 718e94a..3a01203 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -153,5 +153,6 @@ obj-$(CONFIG_MFD_SEC_CORE) += sec-core.o sec-irq.o
> > obj-$(CONFIG_MFD_SYSCON) += syscon.o
> > obj-$(CONFIG_MFD_LM3533) += lm3533-core.o lm3533-ctrlbank.o
> > obj-$(CONFIG_VEXPRESS_CONFIG) += vexpress-config.o vexpress-sysreg.o
> > +obj-$(CONFIG_VEXPRESS_SPC) += vexpress-spc.o
> > obj-$(CONFIG_MFD_RETU) += retu-mfd.o
> > obj-$(CONFIG_MFD_AS3711) += as3711.o
> > diff --git a/drivers/mfd/vexpress-spc.c b/drivers/mfd/vexpress-spc.c
> > new file mode 100644
> > index 0000000..0c6718a
> > --- /dev/null
> > +++ b/drivers/mfd/vexpress-spc.c
> > @@ -0,0 +1,633 @@
> > +/*
> > + * Versatile Express Serial Power Controller (SPC) support
> > + *
> > + * Copyright (C) 2013 ARM Ltd.
> > + *
> > + * Authors: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
> > + * Achin Gupta <achin.gupta@arm.com>
> > + * Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> > + * kind, whether express or implied; without even the implied warranty
> > + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/slab.h>
> > +#include <linux/vexpress.h>
> > +
> > +#include <asm/cacheflush.h>
> > +
> > +#define SCC_CFGREG19 0x120
> > +#define SCC_CFGREG20 0x124
> > +#define A15_CONF 0x400
> > +#define A7_CONF 0x500
> > +#define SYS_INFO 0x700
> > +#define PERF_LVL_A15 0xB00
> > +#define PERF_REQ_A15 0xB04
> > +#define PERF_LVL_A7 0xB08
> > +#define PERF_REQ_A7 0xB0c
> > +#define SYS_CFGCTRL 0xB10
> > +#define SYS_CFGCTRL_REQ 0xB14
> > +#define PWC_STATUS 0xB18
> > +#define PWC_FLAG 0xB1c
> > +#define WAKE_INT_MASK 0xB24
> > +#define WAKE_INT_RAW 0xB28
> > +#define WAKE_INT_STAT 0xB2c
> > +#define A15_PWRDN_EN 0xB30
> > +#define A7_PWRDN_EN 0xB34
> > +#define A7_PWRDNACK 0xB54
> > +#define A15_BX_ADDR0 0xB68
> > +#define SYS_CFG_WDATA 0xB70
> > +#define SYS_CFG_RDATA 0xB74
> > +#define A7_BX_ADDR0 0xB78
>
> These are register offsets? A shared shrot prefix could make that more obvious
> when reading the code below.

Done.

> > +
> > +#define GBL_WAKEUP_INT_MSK (0x3 << 10)
> > +
> > +#define CLKF_SHIFT 16
> > +#define CLKF_MASK 0x1FFF
> > +#define CLKR_SHIFT 0
> > +#define CLKR_MASK 0x3F
> > +#define CLKOD_SHIFT 8
> > +#define CLKOD_MASK 0xF
>
> What registers are these for? Having them defined right below the register
> helps the mental grouping.

CLK* removed, multiplier hardcoded, see below. I will comment on the
wake up mask.

> > +
> > +#define OPP_FUNCTION 6
> > +#define OPP_BASE_DEVICE 0x300
> > +#define OPP_A15_OFFSET 0x4
> > +#define OPP_A7_OFFSET 0xc
> > +
> > +#define SYS_CFGCTRL_START (1 << 31)
> > +#define SYS_CFGCTRL_WRITE (1 << 30)
> > +#define SYS_CFGCTRL_FUNC(n) (((n) & 0x3f) << 20)
> > +#define SYS_CFGCTRL_DEVICE(n) (((n) & 0xfff) << 0)
> > +
> > +#define MAX_OPPS 8
> > +#define MAX_CLUSTERS 2
> > +
> > +enum {
> > + A15_OPP_TYPE = 0,
> > + A7_OPP_TYPE = 1,
> > + SYS_CFGCTRL_TYPE = 2,
> > + INVALID_TYPE
> > +};
>
> Some brief notes about what the OPPs are here would be beneficial.
>
> Also, prefixing makes more sense:
>
> OPP_TYPE_A15
> OPP_TYPE_A7
> ...

Ok.

> > +#define STAT_COMPLETE(type) ((1 << 0) << (type << 2))
> > +#define STAT_ERR(type) ((1 << 1) << (type << 2))
> > +#define RESPONSE_MASK(type) (STAT_COMPLETE(type) | STAT_ERR(type))
> > +
> > +struct vexpress_spc_drvdata {
> > + void __iomem *baseaddr;
> > + u32 a15_clusid;
> > + int irq;
> > + u32 cur_req_type;
> > + u32 freqs[MAX_CLUSTERS][MAX_OPPS];
> > + int freqs_cnt[MAX_CLUSTERS];
>
> Please document the non-obvious ones. Is a15 the dynamic cluster id of the A15
> cluster perhaps?

It is A15-MPIDR[15:8], I will document it.

> > +};
> > +
> > +enum spc_func_type {
> > + CONFIG_FUNC = 0,
> > + PERF_FUNC = 1,
> > +};
> > +
> > +struct vexpress_spc_func {
> > + enum spc_func_type type;
> > + u32 function;
> > + u32 device;
> > +};
> > +
> > +static struct vexpress_spc_drvdata *info;
> > +static u32 *vexpress_spc_config_data;
> > +static struct vexpress_config_bridge *vexpress_spc_config_bridge;
> > +static struct vexpress_config_func *opp_func, *perf_func;
> > +
> > +static int vexpress_spc_load_result = -EAGAIN;
>
> I think Sam already commented on some of these.

Most of them are dynamically allocated now.

> > +
> > +static bool vexpress_spc_initialized(void)
> > +{
> > + return vexpress_spc_load_result == 0;
> > +}
> > +
> > +/**
> > + * vexpress_spc_write_resume_reg() - set the jump address used for warm boot
> > + *
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + * @cpu: mpidr[7:0] bitfield describing cpu affinity level
> > + * @addr: physical resume address
> > + */
> > +void vexpress_spc_write_resume_reg(u32 cluster, u32 cpu, u32 addr)
> > +{
> > + void __iomem *baseaddr;
> > +
> > + if (WARN_ON_ONCE(cluster >= MAX_CLUSTERS))
> > + return;
>
> Do you really need these in every function down the call chain?

I will remove them.

> > +
> > + if (cluster != info->a15_clusid)
>
> You make this test in a bunch of places, I think a helper would be beneficial.
>
> cluster_is_a15(cluster), or whatever.

Done.

> > + baseaddr = info->baseaddr + A7_BX_ADDR0 + (cpu << 2);
> > + else
> > + baseaddr = info->baseaddr + A15_BX_ADDR0 + (cpu << 2);
> > +
> > + writel_relaxed(addr, baseaddr);
> > +}
> > +
> > +/**
> > + * vexpress_spc_get_nb_cpus() - get number of cpus in a cluster
> > + *
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + *
> > + * Return: number of cpus in the cluster
> > + * -EINVAL if cluster number invalid
> > + */
> > +int vexpress_spc_get_nb_cpus(u32 cluster)
>
> Nit: nb_cpus? nr_cpus is more common.

Ok.

> > +{
> > + u32 val;
> > +
> > + if (WARN_ON_ONCE(cluster >= MAX_CLUSTERS))
> > + return -EINVAL;
> > +
> > + val = readl_relaxed(info->baseaddr + SYS_INFO);
> > + val = (cluster != info->a15_clusid) ? (val >> 20) : (val >> 16);
> > + return val & 0xf;
> > +}
> > +EXPORT_SYMBOL_GPL(vexpress_spc_get_nb_cpus);
> > +
> > +/**
> > + * vexpress_spc_get_performance - get current performance level of cluster
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + * @freq: pointer to the performance level to be assigned
>
> Can't you return the perf level instead, with negative for error?

Ok.

> > + *
> > + * Return: 0 on success
> > + * < 0 on read error
> > + */
> > +int vexpress_spc_get_performance(u32 cluster, u32 *freq)
>
> This seems to be a get_freq function, should be named accordingly.

Right, those are leftovers from the conversion from performance level to
frequencies, I will change them.

> > +{
> > + u32 perf_cfg_reg;
> > + int perf, ret;
> > +
> > + if (!vexpress_spc_initialized() || (cluster >= MAX_CLUSTERS))
> > + return -EINVAL;
> > +
> > + perf_cfg_reg = cluster != info->a15_clusid ? PERF_LVL_A7 : PERF_LVL_A15;
> > + ret = vexpress_config_read(perf_func, perf_cfg_reg, &perf);
> > +
> > + if (!ret)
> > + *freq = info->freqs[cluster][perf];
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(vexpress_spc_get_performance);
> > +
> > +/**
> > + * vexpress_spc_get_perf_index - get performance level corresponding to
> > + * a frequency
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + * @freq: frequency to be looked-up
> > + *
> > + * Return: perf level index on success
> > + * -EINVAL on error
> > + */
>
> Can there be such a thing as overdocumenting stuff? Maybe. :-) For trivial
> helpers that don't export an interface it's much better if the code is so
> obvious to read than needing a defined interface.

Agreed.

> I think you'd be better off without the helper here, since it's only used
> a single time.

I am not sure, it is called every time a DVFS OPP is set, maybe it is better
wrapped in a function.

> > +static int vexpress_spc_find_perf_index(u32 cluster, u32 freq)
> > +{
> > + int idx;
> > +
> > + for (idx = 0; idx < info->freqs_cnt[cluster]; idx++)
> > + if (info->freqs[cluster][idx] == freq)
> > + break;
> > + return (idx == info->freqs_cnt[cluster]) ? -EINVAL : idx;
> > +}
> > +
> > +/**
> > + * vexpress_spc_set_performance - set current performance level of cluster
> > + *
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + * @freq: performance level to be programmed
>
> Performance level, or target frequency frequency? Either the help is
> wrong, or the name is confusing.

You are right, see above.

> > + *
> > + * Returns: 0 on success
> > + * < 0 on write error
> > + */
> > +int vexpress_spc_set_performance(u32 cluster, u32 freq)
>
> Again, set_freq() seems more appropriate.

Ditto.

> > +{
> > + int ret, perf, offset;
> > +
> > + if (!vexpress_spc_initialized() || (cluster >= MAX_CLUSTERS))
> > + return -EINVAL;
> > +
> > + offset = (cluster != info->a15_clusid) ? PERF_LVL_A7 : PERF_LVL_A15;
> > +
> > + perf = vexpress_spc_find_perf_index(cluster, freq);
> > +
> > + if (perf < 0 || perf >= MAX_OPPS)
> > + return -EINVAL;
> > +
> > + ret = vexpress_config_write(perf_func, offset, perf);
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(vexpress_spc_set_performance);
> > +
> > +static void vexpress_spc_set_wake_intr(u32 mask)
> > +{
> > + writel_relaxed(mask & VEXPRESS_SPC_WAKE_INTR_MASK,
> > + info->baseaddr + WAKE_INT_MASK);
> > +}
> > +
> > +static inline void reg_bitmask(u32 *reg, u32 mask, bool set)
> > +{
> > + if (set)
> > + *reg |= mask;
> > + else
> > + *reg &= ~mask;
> > +}
> > +
> > +/**
> > + * vexpress_spc_set_global_wakeup_intr()
> > + *
> > + * Function to set/clear global wakeup IRQs. Not protected by locking since
> > + * it might be used in code paths where normal cacheable locks are not
> > + * working. Locking must be provided by the caller to ensure atomicity.
> > + *
> > + * @set: if true, global wake-up IRQs are set, if false they are cleared
> > + */
> > +void vexpress_spc_set_global_wakeup_intr(bool set)
>
> vexpress_spc_set_foo, which passes in "set" which can either be true or false? Say what?

Eh, again leftovers from API refactoring.

> > +{
> > + u32 wake_int_mask_reg = 0;
> > +
> > + wake_int_mask_reg = readl_relaxed(info->baseaddr + WAKE_INT_MASK);
> > + reg_bitmask(&wake_int_mask_reg, GBL_WAKEUP_INT_MSK, set);
>
> This helper just obfuscates, in my opinion.

I will have a look.

> > + vexpress_spc_set_wake_intr(wake_int_mask_reg);
> > +}
> > +
> > +/**
> > + * vexpress_spc_set_cpu_wakeup_irq()
> > + *
> > + * Function to set/clear per-CPU wake-up IRQs. Not protected by locking since
> > + * it might be used in code paths where normal cacheable locks are not
> > + * working. Locking must be provided by the caller to ensure atomicity.
> > + *
> > + * @cpu: mpidr[7:0] bitfield describing cpu affinity level
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + * @set: if true, wake-up IRQs are set, if false they are cleared
> > + */
> > +void vexpress_spc_set_cpu_wakeup_irq(u32 cpu, u32 cluster, bool set)
>
> Same here, set in name vs set argument.

Correct.

> > +{
> > + u32 mask = 0;
> > + u32 wake_int_mask_reg = 0;
> > +
> > + mask = 1 << cpu;
> > + if (info->a15_clusid != cluster)
> > + mask <<= 4;
> > +
> > + wake_int_mask_reg = readl_relaxed(info->baseaddr + WAKE_INT_MASK);
> > + reg_bitmask(&wake_int_mask_reg, mask, set);
> > + vexpress_spc_set_wake_intr(wake_int_mask_reg);
> > +}
> > +
> > +/**
> > + * vexpress_spc_powerdown_enable()
> > + *
> > + * Function to enable/disable cluster powerdown. Not protected by locking
> > + * since it might be used in code paths where normal cacheable locks are not
> > + * working. Locking must be provided by the caller to ensure atomicity.
> > + *
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + * @enable: if true enables powerdown, if false disables it
> > + */
> > +void vexpress_spc_powerdown_enable(u32 cluster, bool enable)
>
> Again with the enable in name vs argument.

Ditto.

> > +{
> > + u32 pwdrn_reg = 0;
> > +
> > + if (cluster >= MAX_CLUSTERS)
> > + return;
> > + pwdrn_reg = cluster != info->a15_clusid ? A7_PWRDN_EN : A15_PWRDN_EN;
> > + writel_relaxed(enable, info->baseaddr + pwdrn_reg);
> > +}
> > +
> > +irqreturn_t vexpress_spc_irq_handler(int irq, void *data)
> > +{
> > + int ret;
> > + u32 status = readl_relaxed(info->baseaddr + PWC_STATUS);
>
> Why readl_relaxed() here? Can't you use a normal readl()?

Nico replied to this.

> > + if (!(status & RESPONSE_MASK(info->cur_req_type)))
> > + return IRQ_NONE;
>
> "pending" is maybe a better term to use than "current" here. I.e. "pending_req"
> as a variable name instead.

Ok.

> > +
> > + if ((status == STAT_COMPLETE(SYS_CFGCTRL_TYPE))
> > + && vexpress_spc_config_data) {
> > + *vexpress_spc_config_data =
> > + readl_relaxed(info->baseaddr + SYS_CFG_RDATA);
> > + vexpress_spc_config_data = NULL;
> > + }
> > +
> > + ret = STAT_COMPLETE(info->cur_req_type) ? 0 : -EIO;

This is a bug, fixed, STAT_COMPLETE should be checked against status.

> > + info->cur_req_type = INVALID_TYPE;
>
> INVALID_TYPE is 3, so the RESPONSE_MASK() check above will pass. That's
> probably not desireable.

Not sure I follow you here, but it helped me unearth the bug above.

> > + vexpress_config_complete(vexpress_spc_config_bridge, ret);
> > + return IRQ_HANDLED;
> > +}
> > +
> > +/**
> > + * Based on the firmware documentation, this is always fixed to 20
>
> What is always fixed to 20? the multiplication factor? So why do we need to get
> it?

Removed.

> > + * All the 4 OSC: A15 PLL0/1, A7 PLL0/1 must be programmed same
> > + * values for both control and value registers.
> > + * This function uses A15 PLL 0 registers to compute multiple factor
> > + * F out = F in * (CLKF + 1) / ((CLKOD + 1) * (CLKR + 1))
> > + */
> > +static inline int __get_mult_factor(void)
>
> __get_opp_freq_unit()?

Gone :-)

> > +{
> > + int i_div, o_div, f_div;
> > + u32 tmp;
> > +
> > + tmp = readl(info->baseaddr + SCC_CFGREG19);
> > + f_div = (tmp >> CLKF_SHIFT) & CLKF_MASK;
> > +
> > + tmp = readl(info->baseaddr + SCC_CFGREG20);
> > + o_div = (tmp >> CLKOD_SHIFT) & CLKOD_MASK;
> > + i_div = (tmp >> CLKR_SHIFT) & CLKR_MASK;
> > +
> > + return (f_div + 1) / ((o_div + 1) * (i_div + 1));
> > +}
> > +
> > +/**
> > + * vexpress_spc_populate_opps() - initialize opp tables from microcontroller
> > + *
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + *
> > + * Return: 0 on success
> > + * < 0 on error
> > + */
> > +static int vexpress_spc_populate_opps(u32 cluster)
> > +{
> > + u32 data = 0, ret, i, offset;
> > + int mult_fact = __get_mult_factor();
> > +
> > + if (WARN_ON_ONCE(cluster >= MAX_CLUSTERS))
> > + return -EINVAL;
> > +
> > + offset = cluster != info->a15_clusid ? OPP_A7_OFFSET : OPP_A15_OFFSET;
> > + for (i = 0; i < MAX_OPPS; i++) {
> > + ret = vexpress_config_read(opp_func, i + offset, &data);
>
> offset + i

Ok.

> > + if (!ret)
> > + info->freqs[cluster][i] = (data & 0xFFFFF) * mult_fact;
> > + else
> > + break;
> > + }
> > +
> > + info->freqs_cnt[cluster] = i;
> > + return ret;
> > +}
> > +
> > +/**
> > + * vexpress_spc_get_freq_table() - Retrieve a pointer to the frequency
> > + * table for a given cluster
> > + *
> > + * @cluster: mpidr[15:8] bitfield describing cluster affinity level
> > + * @fptr: pointer to be initialized
> > + * Return: operating points count on success
> > + * -EINVAL on pointer error
> > + */
> > +int vexpress_spc_get_freq_table(u32 cluster, u32 **fptr)
> > +{
> > + if (WARN_ON_ONCE(!fptr || cluster >= MAX_CLUSTERS))
> > + return -EINVAL;
> > + *fptr = info->freqs[cluster];
> > + return info->freqs_cnt[cluster];
> > +}
> > +EXPORT_SYMBOL_GPL(vexpress_spc_get_freq_table);
>
> Exporting the pointer to the table is a little scary since the caller
> could then modify it. Would be nicer to pass in an array that is
> populated.

Probably better.

> I feel like a hypocrite for having to say this, but here's there's a need for
> docs. You've documented the short trivial functions and not some of the long
> ones... :)

I will do that.

> > +static void *vexpress_spc_func_get(struct device *dev,
> > + struct device_node *node, const char *id)
> > +{
> > + struct vexpress_spc_func *spc_func;
> > + u32 func_device[2];
> > + int err = 0;
> > +
> > + spc_func = kzalloc(sizeof(*spc_func), GFP_KERNEL);
> > + if (!spc_func)
> > + return NULL;
> > +
> > + if (strcmp(id, "opp") == 0) {
> > + spc_func->type = CONFIG_FUNC;
> > + spc_func->function = OPP_FUNCTION;
> > + spc_func->device = OPP_BASE_DEVICE;
> > + } else if (strcmp(id, "perf") == 0) {
> > + spc_func->type = PERF_FUNC;
> > + } else if (node) {
> > + of_node_get(node);
> > + err = of_property_read_u32_array(node,
> > + "arm,vexpress-sysreg,func", func_device,
> > + ARRAY_SIZE(func_device));
> > + of_node_put(node);
> > + spc_func->type = CONFIG_FUNC;
> > + spc_func->function = func_device[0];
> > + spc_func->device = func_device[1];
> > + }
> > +
> > + if (WARN_ON(err)) {
> > + kfree(spc_func);
> > + return NULL;
> > + }
> > +
> > + pr_debug("func 0x%p = 0x%x, %d %d\n", spc_func,
> > + spc_func->function,
> > + spc_func->device,
> > + spc_func->type);
> > +
> > + return spc_func;
> > +}
> > +
> > +static void vexpress_spc_func_put(void *func)
> > +{
> > + kfree(func);
> > +}
> > +
> > +static int vexpress_spc_func_exec(void *func, int offset, bool write,
> > + u32 *data)
> > +{
> > + struct vexpress_spc_func *spc_func = func;
> > + u32 command;
> > +
> > + if (!data)
> > + return -EINVAL;
> > + /*
> > + * Setting and retrieval of operating points is not part of
> > + * DCC config interface. It was made to go through the same
> > + * code path so that requests to the M3 can be serialized
> > + * properly with config reads/writes through the common
> > + * vexpress config interface
> > + */
> > + switch (spc_func->type) {
> > + case PERF_FUNC:
> > + if (write) {
> > + info->cur_req_type = (offset == PERF_LVL_A15) ?
> > + A15_OPP_TYPE : A7_OPP_TYPE;
> > + writel_relaxed(*data, info->baseaddr + offset);
> > + return VEXPRESS_CONFIG_STATUS_WAIT;
> > + } else {
> > + *data = readl_relaxed(info->baseaddr + offset);
> > + return VEXPRESS_CONFIG_STATUS_DONE;
> > + }
> > + case CONFIG_FUNC:
> > + info->cur_req_type = SYS_CFGCTRL_TYPE;
> > +
> > + command = SYS_CFGCTRL_START;
> > + command |= write ? SYS_CFGCTRL_WRITE : 0;
> > + command |= SYS_CFGCTRL_FUNC(spc_func->function);
> > + command |= SYS_CFGCTRL_DEVICE(spc_func->device + offset);
> > +
> > + pr_debug("command %x\n", command);
> > +
> > + if (!write)
> > + vexpress_spc_config_data = data;
> > + else
> > + writel_relaxed(*data, info->baseaddr + SYS_CFG_WDATA);
> > + writel_relaxed(command, info->baseaddr + SYS_CFGCTRL);
> > +
> > + return VEXPRESS_CONFIG_STATUS_WAIT;
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +
> > +struct vexpress_config_bridge_info vexpress_spc_config_bridge_info = {
> > + .name = "vexpress-spc",
> > + .func_get = vexpress_spc_func_get,
> > + .func_put = vexpress_spc_func_put,
> > + .func_exec = vexpress_spc_func_exec,
> > +};
>
> Caveat: I'm running out of time reviewing this one driver, and didn't look into
> the vexpress_config_bridge stuff. Seems like a pretty awkward interface but
> I didn't look closer.

Pawel commented on that code earlier.

> > +
> > +static const struct of_device_id vexpress_spc_ids[] __initconst = {
> > + { .compatible = "arm,vexpress-spc,v2p-ca15_a7" },
> > + { .compatible = "arm,vexpress-spc" },
> > + {},
> > +};
> > +
> > +static int __init vexpress_spc_init(void)
> > +{
> > + int ret;
> > + struct device_node *node = of_find_matching_node(NULL,
> > + vexpress_spc_ids);
> > +
> > + if (!node)
> > + return -ENODEV;
> > +
> > + info = kzalloc(sizeof(*info), GFP_KERNEL);
> > + if (!info) {
> > + pr_err("%s: unable to allocate mem\n", __func__);
> > + return -ENOMEM;
> > + }
> > + info->cur_req_type = INVALID_TYPE;
> > +
> > + info->baseaddr = of_iomap(node, 0);
> > + if (WARN_ON(!info->baseaddr)) {
>
> pr_err() something or other.

Yeah, added for all error conditions below.

> > + ret = -ENXIO;
> > + goto mem_free;
> > + }
> > +
> > + info->irq = irq_of_parse_and_map(node, 0);
> > +
> > + if (WARN_ON(!info->irq)) {
>
> pr_err() something or other.
>
> > + ret = -ENXIO;
> > + goto unmap;
> > + }
> > +
> > + readl_relaxed(info->baseaddr + PWC_STATUS);
> > +
> > + ret = request_irq(info->irq, vexpress_spc_irq_handler,
> > + IRQF_DISABLED | IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> > + "arm-spc", info);
> > +
> > + if (ret) {
> > + pr_err("IRQ %d request failed\n", info->irq);
> > + ret = -ENODEV;
> > + goto unmap;
> > + }
> > +
> > + info->a15_clusid = readl_relaxed(info->baseaddr + A15_CONF) & 0xf;
> > +
> > + vexpress_spc_config_bridge = vexpress_config_bridge_register(
> > + node, &vexpress_spc_config_bridge_info);
> > +
> > + if (WARN_ON(!vexpress_spc_config_bridge)) {
>
> pr_err()
>
> > + ret = -ENODEV;
> > + goto unmap;
> > + }
> > +
> > + opp_func = vexpress_config_func_get(vexpress_spc_config_bridge, "opp");
> > + perf_func =
> > + vexpress_config_func_get(vexpress_spc_config_bridge, "perf");
>
> Your identifiers are so long that you can't fit a simple call on minimum
> indentation without wrapping the line. That should be a pretty strong indicator
> that it needs to be shortened.

Ok, point taken.

> > +
> > + if (!opp_func || !perf_func) {
>
> ...pr_err()
>
> > + ret = -ENODEV;
> > + goto unmap;
> > + }
> > +
> > + if (vexpress_spc_populate_opps(0) || vexpress_spc_populate_opps(1)) {
> > + if (info->irq)
> > + free_irq(info->irq, info);
> > + pr_err("failed to build OPP table\n");
> > + ret = -ENODEV;
> > + goto unmap;
> > + }
> > + /*
> > + * Multi-cluster systems may need this data when non-coherent, during
> > + * cluster power-up/power-down. Make sure it reaches main memory:
> > + */
> > + sync_cache_w(info);
> > + sync_cache_w(&info);
> > + pr_info("vexpress-spc loaded at %p\n", info->baseaddr);
> > + return 0;
> > +
> > +unmap:
> > + iounmap(info->baseaddr);
> > +
> > +mem_free:
> > + kfree(info);
> > + return ret;
> > +}
> > +
> > +static bool __init __vexpress_spc_check_loaded(void);
> > +/*
> > + * Pointer spc_check_loaded is swapped after init hence it is safe
> > + * to initialize it to a function in the __init section
> > + */
> > +static bool (*spc_check_loaded)(void) __refdata = &__vexpress_spc_check_loaded;
> > +
> > +static bool __init __vexpress_spc_check_loaded(void)
> > +{
> > + if (vexpress_spc_load_result == -EAGAIN)
> > + vexpress_spc_load_result = vexpress_spc_init();
> > + spc_check_loaded = &vexpress_spc_initialized;
> > + return vexpress_spc_initialized();
> > +}
>
> Whoa. A "check_foo" function with side effects. Red flag.
>
> So, you only want to try to run vexpress_spc_init() on the very first call to
> spc_check_loaded()? Just do so in vexpress_spc_initalized() instead and keep
> a static bool first_call = true; variable instead. Still confusing and with
> side effects though.

Well, I think the best thing to do is to call it eg spc_init(). That's what it
does anyway and there is no need for syntactic sugar that just hides side
effects.

> > +
> > +/*
> > + * Function exported to manage early_initcall ordering.
> > + * SPC code is needed very early in the boot process
> > + * to bring CPUs out of reset and initialize power
> > + * management back-end. After boot swap pointers to
> > + * make the functionality check available to loadable
> > + * modules, when early boot init functions have been
> > + * already freed from kernel address space.
> > + */
> > +bool vexpress_spc_check_loaded(void)
> > +{
> > + return spc_check_loaded();
> > +}
> > +EXPORT_SYMBOL_GPL(vexpress_spc_check_loaded);
>
> Or, you do that test I mentioned right above here instead.

Commented above.

Thank you very much for the review.
Lorenzo



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