Hi Thierry,
On Mon, Mar 4, 2019 at 1:22 PM, Thierry Reding
<thierry.reding@xxxxxxxxx> wrote:
On Sat, Mar 02, 2019 at 08:33:50PM -0300, Paul Cercueil wrote:
[...]
diff --git a/drivers/clocksource/ingenic-timer.c
b/drivers/clocksource/ingenic-timer.c
[...]
+struct ingenic_tcu {
+ const struct ingenic_soc_info *soc_info;
+ struct regmap *map;
+ struct clk *clk, *timer_clk, *cs_clk;
+
+ struct irq_domain *domain;
+ unsigned int nb_parent_irqs;
+ u32 parent_irqs[3];
+
+ struct clk_hw_onecell_data *clocks;
+
+ unsigned int timer_channel, cs_channel;
+ struct clock_event_device cevt;
+ struct clocksource cs;
+ char name[4];
+
+ unsigned long pwm_channels_mask;
+};
+
+static struct ingenic_tcu *ingenic_tcu;
Is there really a need for this? Seems like the only two reasons for
why
you keep this around are as pointed out below.
+void __iomem *ingenic_tcu_base;
+EXPORT_SYMBOL_GPL(ingenic_tcu_base);
Same here.
+static u64 notrace ingenic_tcu_timer_read(void)
+{
+ unsigned int channel = ingenic_tcu->cs_channel;
+ u16 count;
+
+ count = readw(ingenic_tcu_base + TCU_REG_TCNTc(channel));
Can't yo do this via the regmap?
I could, but for the sched_clock to be precise the function must return
as fast as possible. That's the rationale behind the use of readw()
here.
That's also the reason why ingenic_tcu_base is global and exported, so
that the OS Timer driver can use it as well.
+
+ return count;
+}
+
+static u64 notrace ingenic_tcu_timer_cs_read(struct clocksource
*cs)
+{
+ return ingenic_tcu_timer_read();
+}
And here you've got access to the struct clocksource *, from which you
should be able to get at struct ingenic_tcu * using container_of.
[...]
+static int __init ingenic_tcu_init(struct device_node *np)
+{
+ const struct of_device_id *id =
of_match_node(ingenic_tcu_of_match, np);
+ const struct ingenic_soc_info *soc_info = id->data;
+ struct ingenic_tcu *tcu;
+ struct resource res;
+ void __iomem *base;
+ long rate;
+ int ret;
+
+ of_node_clear_flag(np, OF_POPULATED);
+
+ tcu = kzalloc(sizeof(*tcu), GFP_KERNEL);
+ if (!tcu)
+ return -ENOMEM;
+
+ /* Enable all TCU channels for PWM use by default except channel 0
+ * and channel 1.
+ */
+ tcu->pwm_channels_mask = GENMASK(soc_info->num_channels - 1, 2);
+ of_property_read_u32(np, "ingenic,pwm-channels-mask",
+ (u32 *)&tcu->pwm_channels_mask);
+
+ /* Verify that we have at least two free channels */
+ if (hweight8(tcu->pwm_channels_mask) > soc_info->num_channels -
2) {
+ pr_crit("ingenic-tcu: Invalid PWM channel mask: 0x%02lx\n",
+ tcu->pwm_channels_mask);
+ return -EINVAL;
+ }
+
+ tcu->soc_info = soc_info;
+ ingenic_tcu = tcu;
+
+ tcu->timer_channel = find_first_zero_bit(&tcu->pwm_channels_mask,
+ soc_info->num_channels);
+ tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
+ soc_info->num_channels,
+ tcu->timer_channel + 1);
+
+ base = of_io_request_and_map(np, 0, NULL);
+ if (IS_ERR(base)) {
+ ret = PTR_ERR(base);
+ goto err_free_ingenic_tcu;
+ }
+
+ of_address_to_resource(np, 0, &res);
+
+ ingenic_tcu_base = base;
+
+ tcu->map = regmap_init_mmio(NULL, base,
&ingenic_tcu_regmap_config);
+ if (IS_ERR(tcu->map)) {
+ ret = PTR_ERR(tcu->map);
+ goto err_iounmap;
+ }
+
+ tcu->clk = of_clk_get_by_name(np, "tcu");
+ if (IS_ERR(tcu->clk)) {
+ ret = PTR_ERR(tcu->clk);
+ pr_crit("ingenic-tcu: Unable to find TCU clock: %i\n", ret);
+ goto err_free_regmap;
+ }
+
+ ret = clk_prepare_enable(tcu->clk);
+ if (ret) {
+ pr_crit("ingenic-tcu: Unable to enable TCU clock: %i\n", ret);
+ goto err_clk_put;
+ }
+
+ ret = ingenic_tcu_intc_init(tcu, np);
+ if (ret)
+ goto err_clk_disable;
+
+ ret = ingenic_tcu_clk_init(tcu, np);
+ if (ret)
+ goto err_tcu_intc_cleanup;
+
+ ret = ingenic_tcu_clocksource_init(tcu);
+ if (ret)
+ goto err_tcu_clk_cleanup;
+
+ ret = ingenic_tcu_timer_init(tcu);
+ if (ret)
+ goto err_tcu_clocksource_cleanup;
+
+ // Register the sched_clock at the very end as there's no way to
undo it
+ rate = clk_get_rate(tcu->cs_clk);
+ sched_clock_register(ingenic_tcu_timer_read, 16, rate);
Oh wow... so you managed to nicely encapsulate everything and now this
seems to be the only reason why you need to rely on global variables.
That's unfortunate. I suppose we could go and add a void *data
parameter
to sched_clock_register() and pass that to the read() function. That
way
you could make this completely independent of global variables, but
there are 73 callers of sched_clock_register() and they are spread all
over the place, so sounds a bit daunting to me.
Yes, that's the main reason behind the use of a global variables.
Is there a way we could introduce another callback, e.g. .read_value(),
that would receive a void *param? Then the current .read() callback
can be deprecated and the 73 callers can be migrated later.
+
+ return 0;
+
+err_tcu_clocksource_cleanup:
+ ingenic_tcu_clocksource_cleanup(tcu);
+err_tcu_clk_cleanup:
+ ingenic_tcu_clk_cleanup(tcu, np);
+err_tcu_intc_cleanup:
+ ingenic_tcu_intc_cleanup(tcu);
+err_clk_disable:
+ clk_disable_unprepare(tcu->clk);
+err_clk_put:
+ clk_put(tcu->clk);
+err_free_regmap:
+ regmap_exit(tcu->map);
+err_iounmap:
+ iounmap(base);
+ release_mem_region(res.start, resource_size(&res));
+err_free_ingenic_tcu:
+ kfree(tcu);
+ return ret;
+}
+
+TIMER_OF_DECLARE(jz4740_tcu_intc, "ingenic,jz4740-tcu",
ingenic_tcu_init);
+TIMER_OF_DECLARE(jz4725b_tcu_intc, "ingenic,jz4725b-tcu",
ingenic_tcu_init);
+TIMER_OF_DECLARE(jz4770_tcu_intc, "ingenic,jz4770-tcu",
ingenic_tcu_init);
+
+
+static int __init ingenic_tcu_probe(struct platform_device *pdev)
+{
+ platform_set_drvdata(pdev, ingenic_tcu);
Then there's also this. Oh well... nevermind then.
The content of ingenic_tcu_platform_init() could be moved inside
ingenic_tcu_init(). But can we get a hold of the struct device before
the
probe function is called? That would allow to set the drvdata and regmap
without relying on global state.
+bool ingenic_tcu_pwm_can_use_chn(unsigned int channel)
+{
+ return !!(ingenic_tcu->pwm_channels_mask & BIT(channel));
+}
+EXPORT_SYMBOL_GPL(ingenic_tcu_pwm_can_use_chn);
I wonder if we could make this slightly nicer, though. Judging by the
name, this one seems like it would only ever be used by the PWM. If
the
PWM is a child of the TCU, could it not pass in a struct device * that
points to its parent into this? Or perhaps pass its own struct device
*
and have this function look up the struct ingenic_tcu from that?
Should
be something trivial as:
bool ingenic_tcu_pwm_can_use_channel(struct device *dev, unsigned
int channel)
{
struct ingenic_tcu *tcu = dev_get_drvdata(dev->parent);
return !!(tcu->pwm_channels_mask & BIT(channel));
}
Thierry
Yes, that definitely looks better. Thanks for the hint.
-Paul
