Re: [PATCH v13 05/13] clk: ingenic: Add driver for the TCU clocks

From: Paul Cercueil
Date: Tue Jun 25 2019 - 18:37:21 EST



Le mer. 26 juin 2019 à 0:09, Stephen Boyd <sboyd@xxxxxxxxxx> a écrit :
Quoting Paul Cercueil (2019-06-24 15:57:51)
diff --git a/drivers/clk/ingenic/tcu.c b/drivers/clk/ingenic/tcu.c
new file mode 100644
index 000000000000..6d667c4a2bd5
--- /dev/null
+++ b/drivers/clk/ingenic/tcu.c
@@ -0,0 +1,473 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * JZ47xx SoCs TCU clocks driver
+ * Copyright (C) 2019 Paul Cercueil <paul@xxxxxxxxxxxxxxx>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clockchips.h>
+#include <linux/mfd/ingenic-tcu.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/syscore_ops.h>
+
+#include <dt-bindings/clock/ingenic,tcu.h>
+
[...]
+
+static const struct ingenic_soc_info jz4740_soc_info = {
+ .num_channels = 8,
+ .has_ost = false,
+ .has_tcu_clk = true,
+};
+
+static const struct ingenic_soc_info jz4725b_soc_info = {
+ .num_channels = 6,
+ .has_ost = true,
+ .has_tcu_clk = true,
+};
+
+static const struct ingenic_soc_info jz4770_soc_info = {
+ .num_channels = 8,
+ .has_ost = true,
+ .has_tcu_clk = false,
+};
+
+static const struct of_device_id ingenic_tcu_of_match[] __initconst = {
+ { .compatible = "ingenic,jz4740-tcu", .data = &jz4740_soc_info, },
+ { .compatible = "ingenic,jz4725b-tcu", .data = &jz4725b_soc_info, },
+ { .compatible = "ingenic,jz4770-tcu", .data = &jz4770_soc_info, },
+ { }
+};
+
+static int __init ingenic_tcu_probe(struct device_node *np)
+{
+ const struct of_device_id *id = of_match_node(ingenic_tcu_of_match, np);
+ struct ingenic_tcu *tcu;
+ struct regmap *map;
+ unsigned int i;
+ int ret;
+
+ map = ingenic_tcu_get_regmap(np);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ tcu = kzalloc(sizeof(*tcu), GFP_KERNEL);
+ if (!tcu)
+ return -ENOMEM;
+
+ tcu->map = map;
+ tcu->soc_info = id->data;
+
+ if (tcu->soc_info->has_tcu_clk) {
+ tcu->clk = of_clk_get_by_name(np, "tcu");

Do you need to get the clk by name? Or can that clk be "known" to the
TCU somehow so we can already have a direct clk pointer?

This clock is provided by a separate driver, so I have to obtain the
clock pointer from devicetree.


+ if (IS_ERR(tcu->clk)) {
+ ret = PTR_ERR(tcu->clk);
+ pr_crit("Cannot get TCU clock\n");
+ goto err_free_tcu;
+ }
+
+ ret = clk_prepare_enable(tcu->clk);
+ if (ret) {
+ pr_crit("Unable to enable TCU clock\n");
+ goto err_put_clk;
+ }
+ }
+
+ tcu->clocks = kzalloc(sizeof(*tcu->clocks) +
+ sizeof(*tcu->clocks->hws) * TCU_CLK_COUNT,
+ GFP_KERNEL);
+ if (!tcu->clocks) {
+ ret = -ENOMEM;
+ goto err_clk_disable;
+ }
+
+ tcu->clocks->num = TCU_CLK_COUNT;
+
+ for (i = 0; i < tcu->soc_info->num_channels; i++) {
+ ret = ingenic_tcu_register_clock(tcu, i, TCU_PARENT_EXT,
+ &ingenic_tcu_clk_info[i],
+ tcu->clocks);
+ if (ret) {
+ pr_crit("cannot register clock %i\n", i);
+ goto err_unregister_timer_clocks;
+ }
+ }
+
+ /*
+ * We set EXT as the default parent clock for all the TCU clocks
+ * except for the watchdog one, where we set the RTC clock as the
+ * parent. Since the EXT and PCLK are much faster than the RTC clock,
+ * the watchdog would kick after a maximum time of 5s, and we might
+ * want a slower kicking time.
+ */
+ ret = ingenic_tcu_register_clock(tcu, TCU_CLK_WDT, TCU_PARENT_RTC,
+ &ingenic_tcu_watchdog_clk_info,
+ tcu->clocks);
+ if (ret) {
+ pr_crit("cannot register watchdog clock\n");
+ goto err_unregister_timer_clocks;
+ }
+
+ if (tcu->soc_info->has_ost) {
+ ret = ingenic_tcu_register_clock(tcu, TCU_CLK_OST,
+ TCU_PARENT_EXT,
+ &ingenic_tcu_ost_clk_info,
+ tcu->clocks);
+ if (ret) {
+ pr_crit("cannot register ost clock\n");
+ goto err_unregister_watchdog_clock;
+ }
+ }
+
+ ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, tcu->clocks);
+ if (ret) {
+ pr_crit("cannot add OF clock provider\n");
+ goto err_unregister_ost_clock;
+ }
+
+ ingenic_tcu = tcu;
+
+ return 0;
+
+err_unregister_ost_clock:
+ if (tcu->soc_info->has_ost)
+ clk_hw_unregister(tcu->clocks->hws[i + 1]);
+err_unregister_watchdog_clock:
+ clk_hw_unregister(tcu->clocks->hws[i]);
+err_unregister_timer_clocks:
+ for (i = 0; i < tcu->clocks->num; i++)
+ if (tcu->clocks->hws[i])
+ clk_hw_unregister(tcu->clocks->hws[i]);
+ kfree(tcu->clocks);
+err_clk_disable:
+ if (tcu->soc_info->has_tcu_clk)
+ clk_disable_unprepare(tcu->clk);
+err_put_clk:
+ if (tcu->soc_info->has_tcu_clk)
+ clk_put(tcu->clk);
+err_free_tcu:
+ kfree(tcu);
+ return ret;

Too bad this isn't a device with devm!

+}
+
+static int __maybe_unused tcu_pm_suspend(void)
+{
+ struct ingenic_tcu *tcu = ingenic_tcu;
+
+ if (tcu->clk)
+ clk_disable(tcu->clk);

Do you need to unprepare? Or it just isn't possible because this is
called from syscore and thus we can't sleep?

I thought that clk_disable() was enough. We don't actually need to
unprepare, do we? And yes, as you pointed out, this call cannot sleep.

+
+ return 0;
+}
+
+static void __maybe_unused tcu_pm_resume(void)
+{
+ struct ingenic_tcu *tcu = ingenic_tcu;
+
+ if (tcu->clk)
+ clk_enable(tcu->clk);
+}
+
+static struct syscore_ops __maybe_unused tcu_pm_ops = {
+ .suspend = tcu_pm_suspend,
+ .resume = tcu_pm_resume,
+};
+
+static void __init ingenic_tcu_init(struct device_node *np)
+{
+ int ret = ingenic_tcu_probe(np);
+
+ if (ret)
+ pr_crit("Failed to initialize TCU clocks: %i\n", ret);

Should be %d instead of %i? Applies to all this file.

OK.

Thanks,
-Paul

+
+ if (IS_ENABLED(CONFIG_PM_SLEEP))
+ register_syscore_ops(&tcu_pm_ops);
+}