Re: [PATCH v4 7/8] clocksource: Add a new timer-ingenic driver

From: Paul Cercueil
Date: Wed Mar 28 2018 - 11:16:05 EST

Le 2018-03-24 07:26, Daniel Lezcano a ÃcritÂ:
On 18/03/2018 00:29, Paul Cercueil wrote:
This driver will use the TCU (Timer Counter Unit) present on the Ingenic
JZ47xx SoCs to provide the kernel with a clocksource and timers.

Please provide a more detailed description about the timer.

There's a doc file for that :)

Where is the clocksource ?

Right, there is no clocksource, just timers.

I don't see the point of using channel idx and pwm checking here.

There is one clockevent, why create multiple channels ? Can't you stick
to the usual init routine for a timer.

So the idea is that we use all the TCU channels that won't be used for PWM
as timers. Hence the PWM checking. Why is this bad?

Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---
drivers/clocksource/Kconfig | 8 ++
drivers/clocksource/Makefile | 1 +
drivers/clocksource/timer-ingenic.c | 278 ++++++++++++++++++++++++++++++++++++
3 files changed, 287 insertions(+)
create mode 100644 drivers/clocksource/timer-ingenic.c

v2: Use SPDX identifier for the license
v3: - Move documentation to its own patch
- Search the devicetree for PWM clients, and use all the TCU
channels that won't be used for PWM
v4: - Add documentation about why we search for PWM clients
- Verify that the PWM clients are for the TCU PWM driver

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index d2e5382821a4..481422145fb4 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -592,4 +592,12 @@ config CLKSRC_ST_LPC
Enable this option to use the Low Power controller timer
as clocksource.

+config INGENIC_TIMER
+ bool "Clocksource/timer using the TCU in Ingenic JZ SoCs"
+ depends on MACH_INGENIC || COMPILE_TEST

bool "Clocksource/timer using the TCU in Ingenic JZ SoCs" if COMPILE_TEST

Remove the depends MACH_INGENIC.

This driver is not useful on anything else than Ingenic SoCs, why should I
remove MACH_INGENIC then?

+ select CLKSRC_OF
+ default y

No default, Kconfig platform selects the timer.

Alright.

+ help
+ Support for the timer/counter unit of the Ingenic JZ SoCs.
+
endmenu
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index d6dec4489d66..98691e8999fe 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -74,5 +74,6 @@ obj-$(CONFIG_ASM9260_TIMER) += asm9260_timer.o
obj-$(CONFIG_H8300_TMR8) += h8300_timer8.o
obj-$(CONFIG_H8300_TMR16) += h8300_timer16.o
obj-$(CONFIG_H8300_TPU) += h8300_tpu.o
+obj-$(CONFIG_INGENIC_TIMER) += timer-ingenic.o
obj-$(CONFIG_CLKSRC_ST_LPC) += clksrc_st_lpc.o
obj-$(CONFIG_X86_NUMACHIP) += numachip.o
diff --git a/drivers/clocksource/timer-ingenic.c b/drivers/clocksource/timer-ingenic.c
new file mode 100644
index 000000000000..8c777c0c0023
--- /dev/null
+++ b/drivers/clocksource/timer-ingenic.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Ingenic JZ47xx SoC TCU clocksource driver
+ * Copyright (C) 2018 Paul Cercueil <paul@xxxxxxxxxxxxxxx>
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mfd/syscon/ingenic-tcu.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define NUM_CHANNELS 8
+
+struct ingenic_tcu;
+
+struct ingenic_tcu_channel {
+ unsigned int idx;
+ struct clk *clk;
+};
+
+struct ingenic_tcu {
+ struct ingenic_tcu_channel channels[NUM_CHANNELS];
+ unsigned long requested;
+ struct regmap *map;
+};
+
+struct ingenic_clock_event_device {
+ struct clock_event_device cevt;
+ struct ingenic_tcu_channel *channel;
+ char name[32];
+};
+
+#define ingenic_cevt(_evt) \
+ container_of(_evt, struct ingenic_clock_event_device, cevt)
+
+static inline struct ingenic_tcu *to_ingenic_tcu(struct ingenic_tcu_channel *ch)
+{
+ return container_of(ch, struct ingenic_tcu, channels[ch->idx]);
+}
+
+static int ingenic_tcu_cevt_set_state_shutdown(struct clock_event_device *evt)
+{
+ struct ingenic_clock_event_device *jzcevt = ingenic_cevt(evt);
+ struct ingenic_tcu_channel *channel = jzcevt->channel;
+ struct ingenic_tcu *tcu = to_ingenic_tcu(channel);
+ unsigned int idx = channel->idx;
+
+ regmap_write(tcu->map, TCU_REG_TECR, BIT(idx));
+ return 0;
+}
+
+static int ingenic_tcu_cevt_set_next(unsigned long next,
+ struct clock_event_device *evt)
+{
+ struct ingenic_clock_event_device *jzcevt = ingenic_cevt(evt);
+ struct ingenic_tcu_channel *channel = jzcevt->channel;
+ struct ingenic_tcu *tcu = to_ingenic_tcu(channel);
+ unsigned int idx = channel->idx;
+
+ if (next > 0xffff)
+ return -EINVAL;
+
+ regmap_write(tcu->map, TCU_REG_TDFRc(idx), (unsigned int) next);
+ regmap_write(tcu->map, TCU_REG_TCNTc(idx), 0);
+ regmap_write(tcu->map, TCU_REG_TESR, BIT(idx));
+
+ return 0;
+}
+
+static irqreturn_t ingenic_tcu_cevt_cb(int irq, void *dev_id)
+{
+ struct clock_event_device *cevt = dev_id;
+ struct ingenic_clock_event_device *jzcevt = ingenic_cevt(cevt);
+ struct ingenic_tcu_channel *channel = jzcevt->channel;
+ struct ingenic_tcu *tcu = to_ingenic_tcu(channel);
+ unsigned int idx = channel->idx;
+
+ regmap_write(tcu->map, TCU_REG_TECR, BIT(idx));
+
+ if (cevt->event_handler)
+ cevt->event_handler(cevt);
+
+ return IRQ_HANDLED;
+}
+
+static int __init ingenic_tcu_req_channel(struct ingenic_tcu_channel *channel)
+{
+ struct ingenic_tcu *tcu = to_ingenic_tcu(channel);
+ char buf[16];
+ int err;
+
+ if (test_and_set_bit(channel->idx, &tcu->requested))
+ return -EBUSY;
+
+ snprintf(buf, sizeof(buf), "timer%u", channel->idx);
+ channel->clk = clk_get(NULL, buf);
+ if (IS_ERR(channel->clk)) {
+ err = PTR_ERR(channel->clk);
+ goto out_release;
+ }
+
+ err = clk_prepare_enable(channel->clk);
+ if (err)
+ goto out_clk_put;
+
+ return 0;
+
+out_clk_put:
+ clk_put(channel->clk);
+out_release:
+ clear_bit(channel->idx, &tcu->requested);
+ return err;
+}
+
+static int __init ingenic_tcu_reset_channel(struct device_node *np,
+ struct ingenic_tcu_channel *channel)
+{
+ struct ingenic_tcu *tcu = to_ingenic_tcu(channel);
+
+ return regmap_update_bits(tcu->map, TCU_REG_TCSRc(channel->idx),
+ 0xffff & ~TCU_TCSR_RESERVED_BITS, 0);
+}
+
+static void __init ingenic_tcu_free_channel(struct ingenic_tcu_channel *channel)
+{
+ struct ingenic_tcu *tcu = to_ingenic_tcu(channel);
+
+ clk_disable_unprepare(channel->clk);
+ clk_put(channel->clk);
+ clear_bit(channel->idx, &tcu->requested);
+}
+
+static const char * const ingenic_tcu_timer_names[] = {
+ "TCU0", "TCU1", "TCU2", "TCU3", "TCU4", "TCU5", "TCU6", "TCU7",
+};
+
+static int __init ingenic_tcu_setup_cevt(struct device_node *np,
+ struct ingenic_tcu *tcu, unsigned int idx)
+{
+ struct ingenic_tcu_channel *channel = &tcu->channels[idx];
+ struct ingenic_clock_event_device *jzcevt;
+ unsigned long rate;
+ int err, virq;
+
+ err = ingenic_tcu_req_channel(channel);
+ if (err)
+ return err;
+
+ err = ingenic_tcu_reset_channel(np, channel);
+ if (err)
+ goto err_out_free_channel;
+
+ rate = clk_get_rate(channel->clk);
+ if (!rate) {
+ err = -EINVAL;
+ goto err_out_free_channel;
+ }
+
+ jzcevt = kzalloc(sizeof(*jzcevt), GFP_KERNEL);
+ if (!jzcevt) {
+ err = -ENOMEM;
+ goto err_out_free_channel;
+ }
+
+ virq = irq_of_parse_and_map(np, idx);
+ if (!virq) {
+ err = -EINVAL;
+ goto err_out_kfree_jzcevt;
+ }
+
+ err = request_irq(virq, ingenic_tcu_cevt_cb, IRQF_TIMER,
+ ingenic_tcu_timer_names[idx], &jzcevt->cevt);
+ if (err)
+ goto err_out_irq_dispose_mapping;
+
+ jzcevt->channel = channel;
+ snprintf(jzcevt->name, sizeof(jzcevt->name), "ingenic-tcu-chan%u",
+ channel->idx);
+
+ jzcevt->cevt.cpumask = cpumask_of(smp_processor_id());
+ jzcevt->cevt.features = CLOCK_EVT_FEAT_ONESHOT;
+ jzcevt->cevt.name = jzcevt->name;
+ jzcevt->cevt.rating = 200;
+ jzcevt->cevt.set_state_shutdown = ingenic_tcu_cevt_set_state_shutdown;
+ jzcevt->cevt.set_next_event = ingenic_tcu_cevt_set_next;
+
+ clockevents_config_and_register(&jzcevt->cevt, rate, 10, (1 << 16) - 1);
+
+ return 0;
+
+err_out_irq_dispose_mapping:
+ irq_dispose_mapping(virq);
+err_out_kfree_jzcevt:
+ kfree(jzcevt);
+err_out_free_channel:
+ ingenic_tcu_free_channel(channel);
+ return err;
+}
+
+static int __init ingenic_tcu_init(struct device_node *np)
+{
+ unsigned long available_channels = GENMASK(NUM_CHANNELS - 1, 0);
+ struct device_node *node, *pwm_driver_node;
+ struct ingenic_tcu *tcu;
+ unsigned int i, channel;
+ int err;
+ u32 val;
+
+ /* Parse the devicetree for clients of the TCU PWM driver;
+ * every TCU channel not requested for PWM will be used as
+ * a timer.
+ */



+ for_each_node_with_property(node, "pwms") {
+ /* Get the PWM channel ID (field 1 of the "pwms" node) */
+ err = of_property_read_u32_index(node, "pwms", 1, &val);
+ if (!err && val >= NUM_CHANNELS)
+ err = -EINVAL;
+ if (err) {
+ pr_err("timer-ingenic: Unable to parse PWM nodes!");
+ break;
+ }
+
+ /* Get the PWM driver node (field 0 of the "pwms" node) */
+ pwm_driver_node = of_parse_phandle(node, "pwms", 0);
+ if (!pwm_driver_node) {
+ pr_err("timer-ingenic: Unable to find PWM driver node");
+ break;
+ }
+
+ /* Verify that the node we found is for the TCU PWM driver,
+ * by checking that this driver and the PWM driver passed
+ * as phandle share the same parent (the "ingenic,tcu"
+ * compatible MFD/syscon node).
+ */
+ if (pwm_driver_node->parent != np->parent)
+ continue;
+
+ pr_info("timer-ingenic: Reserving channel %u for PWM", val);
+ available_channels &= ~BIT(val);
+ }
+
+ tcu = kzalloc(sizeof(*tcu), GFP_KERNEL);
+ if (!tcu)
+ return -ENOMEM;
+
+ tcu->map = syscon_node_to_regmap(np->parent);
+ if (IS_ERR(tcu->map)) {
+ err = PTR_ERR(tcu->map);
+ kfree(tcu);
+ return err;
+ }
+
+ for (i = 0; i < NUM_CHANNELS; i++)
+ tcu->channels[i].idx = i;

I'm pretty sure you can do better thaningenic_tcu_setup that :)

I didn't think this would be a problem. I guess I can try.

+ for_each_set_bit(channel, &available_channels, NUM_CHANNELS) {
+ err = _cevt(np, tcu, channel);
+ if (err) {
+ pr_warn("timer-ingenic: Unable to init TCU channel %u: %i",
+ channel, err);
+ continue;
+ }
+ }
+
+ return 0;
+}
+
+/* We only probe via devicetree, no need for a platform driver */
+CLOCKSOURCE_OF_DECLARE(jz4740_tcu, "ingenic,jz4740-tcu", ingenic_tcu_init);
+CLOCKSOURCE_OF_DECLARE(jz4770_tcu, "ingenic,jz4770-tcu", ingenic_tcu_init);
+CLOCKSOURCE_OF_DECLARE(jz4780_tcu, "ingenic,jz4780-tcu", ingenic_tcu_init);

s/CLOCKSOURCE_OF_DECLARE/TIMER_OF_DECLARE/

Sure, OK.

Thanks!
-Paul