Re: [PATCH V5] clk: bcm: Add driver for BCM53573 ILP clock
From: Stephen Boyd <hidden>
Date: 2016-08-24 08:58:11
Also in:
linux-clk, lkml
On 08/23, Rafał Miłecki wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c new file mode 100644 index 0000000..b7ac0eb --- /dev/null +++ b/drivers/clk/bcm/clk-bcm53573-ilp.c@@ -0,0 +1,146 @@ +/* + * Copyright (C) 2016 Rafał Miłecki <rafal-g1n6cQUeyibVItvQsEIGlw@public.gmane.org> + * + * 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. + */ + +#include <linux/clk.h>
Is this include used?
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+#define PMU_XTAL_FREQ_RATIO 0x66c
+#define XTAL_ALP_PER_4ILP 0x00001fff
+#define XTAL_CTL_EN 0x80000000
+#define PMU_SLOW_CLK_PERIOD 0x6dc
+
+struct bcm53573_ilp {
+ struct clk *clk;
+ struct clk_hw hw;
+ void __iomem *pmu;
+};
+
+static int bcm53573_ilp_enable(struct clk_hw *hw)
+{
+ struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+
+ writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
+ writel(0x10000, ilp->pmu + 0x674);Is there a name for 0x674?
+
+ return 0;
+}
+
+static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
+ void __iomem *pmu = ilp->pmu;
+ u32 last_val, cur_val;
+ u32 sum = 0, num = 0, loop_num = 0;Should these just be plain ints? Do we care about sizes for these variables?
+ u32 avg;
This one too.
+
+ /* Enable measurement */
+ writel(XTAL_CTL_EN, pmu + PMU_XTAL_FREQ_RATIO);
+
+ /* Read initial value */
+ last_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+ /*
+ * At minimum we should loop for a bit to let hardware do the
+ * measurement. This isn't very accurate however, so for a better
+ * precision lets try getting 20 different values for and use average.
+ */
+ while (num < 20) {
+ cur_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
+
+ if (cur_val != last_val) {
+ /* Got different value, use it */
+ sum += cur_val;
+ num++;
+ loop_num = 0;
+ last_val = cur_val;
+ } else if (++loop_num > 5000) {
+ /* Same value over and over, give up */
+ sum += cur_val;
+ num++;
+ break;
+ }Should there be a udelay() here? Or we're expected to tight loop read the hardware? If so we should throw in a cpu_relax() here to indicate tight loop.
+ }
+
+ /* Disable measurement to save power */
+ writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
+
+ avg = sum / num;
+
+ return parent_rate * 4 / avg;
+}
+
+static const struct clk_ops bcm53573_ilp_clk_ops = {
+ .enable = bcm53573_ilp_enable,No disable? Or .is_enabled?
+ .recalc_rate = bcm53573_ilp_recalc_rate,
+};
+
+static void bcm53573_ilp_init(struct device_node *np)
+{
+ struct bcm53573_ilp *ilp;
+ struct resource res;
+ struct clk_init_data init = { 0 };
+ const char *parent_name;
+ int index;
+ int err;
+
+ ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
+ if (!ilp)
+ return;
+
+ parent_name = of_clk_get_parent_name(np, 0);
+ if (!parent_name) {
+ err = -ENOENT;
+ goto err_free_ilp;
+ }
+
+ /* TODO: This looks generic, try making it OF helper. */
+ index = of_property_match_string(np, "reg-names", "pmu");
+ if (index < 0) {
+ err = index;
+ goto err_free_ilp;
+ }
+ err = of_address_to_resource(np, index, &res);
+ if (err)
+ goto err_free_ilp;
+ ilp->pmu = ioremap(res.start, resource_size(&res));
+ if (IS_ERR(ilp->pmu)) {
+ err = PTR_ERR(ilp->pmu);
+ goto err_free_ilp;
+ }
+
+ init.name = np->name;
+ init.ops = &bcm53573_ilp_clk_ops;
+ init.parent_names = &parent_name;
+ init.num_parents = 1;
+
+ ilp->hw.init = &init;
+ ilp->clk = clk_register(NULL, &ilp->hw);please use clk_hw_register() and of_clk_add_hw_provider().
+ if (WARN_ON(IS_ERR(ilp->clk)))
+ goto err_unmap_pmu;
+
+ err = of_clk_add_provider(np, of_clk_src_simple_get, ilp->clk);
+ if (err)
+ goto err_clk_unregister;
+
+ return;
+
+err_clk_unregister:
+ clk_unregister(ilp->clk);
+err_unmap_pmu:
+ iounmap(ilp->pmu);
+err_free_ilp:
+ kfree(ilp);
+ pr_err("Failed to init ILP clock: %d\n", err);
+}
+CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);Can this be a platform driver instead? -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html