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path: root/drivers/clk/tegra/clk-tegra20-emc.c
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-rw-r--r--drivers/clk/tegra/clk-tegra20-emc.c293
1 files changed, 293 insertions, 0 deletions
diff --git a/drivers/clk/tegra/clk-tegra20-emc.c b/drivers/clk/tegra/clk-tegra20-emc.c
new file mode 100644
index 000000000000..03bf0009a33c
--- /dev/null
+++ b/drivers/clk/tegra/clk-tegra20-emc.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Based on drivers/clk/tegra/clk-emc.c
+ * Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved.
+ *
+ * Author: Dmitry Osipenko <digetx@gmail.com>
+ * Copyright (C) 2019 GRATE-DRIVER project
+ */
+
+#define pr_fmt(fmt) "tegra-emc-clk: " fmt
+
+#include <linux/bits.h>
+#include <linux/clk-provider.h>
+#include <linux/clk/tegra.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "clk.h"
+
+#define CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK GENMASK(7, 0)
+#define CLK_SOURCE_EMC_2X_CLK_SRC_MASK GENMASK(31, 30)
+#define CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT 30
+
+#define MC_EMC_SAME_FREQ BIT(16)
+#define USE_PLLM_UD BIT(29)
+
+#define EMC_SRC_PLL_M 0
+#define EMC_SRC_PLL_C 1
+#define EMC_SRC_PLL_P 2
+#define EMC_SRC_CLK_M 3
+
+static const char * const emc_parent_clk_names[] = {
+ "pll_m", "pll_c", "pll_p", "clk_m",
+};
+
+struct tegra_clk_emc {
+ struct clk_hw hw;
+ void __iomem *reg;
+ bool mc_same_freq;
+ bool want_low_jitter;
+
+ tegra20_clk_emc_round_cb *round_cb;
+ void *cb_arg;
+};
+
+static inline struct tegra_clk_emc *to_tegra_clk_emc(struct clk_hw *hw)
+{
+ return container_of(hw, struct tegra_clk_emc, hw);
+}
+
+static unsigned long emc_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+ u32 val, div;
+
+ val = readl_relaxed(emc->reg);
+ div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+
+ return DIV_ROUND_UP(parent_rate * 2, div + 2);
+}
+
+static u8 emc_get_parent(struct clk_hw *hw)
+{
+ struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+
+ return readl_relaxed(emc->reg) >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+}
+
+static int emc_set_parent(struct clk_hw *hw, u8 index)
+{
+ struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+ u32 val, div;
+
+ val = readl_relaxed(emc->reg);
+ val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
+ val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+
+ div = val & CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+
+ if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
+ val |= USE_PLLM_UD;
+ else
+ val &= ~USE_PLLM_UD;
+
+ if (emc->mc_same_freq)
+ val |= MC_EMC_SAME_FREQ;
+ else
+ val &= ~MC_EMC_SAME_FREQ;
+
+ writel_relaxed(val, emc->reg);
+
+ fence_udelay(1, emc->reg);
+
+ return 0;
+}
+
+static int emc_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+ unsigned int index;
+ u32 val, div;
+
+ div = div_frac_get(rate, parent_rate, 8, 1, 0);
+
+ val = readl_relaxed(emc->reg);
+ val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+ val |= div;
+
+ index = val >> CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+
+ if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
+ val |= USE_PLLM_UD;
+ else
+ val &= ~USE_PLLM_UD;
+
+ if (emc->mc_same_freq)
+ val |= MC_EMC_SAME_FREQ;
+ else
+ val &= ~MC_EMC_SAME_FREQ;
+
+ writel_relaxed(val, emc->reg);
+
+ fence_udelay(1, emc->reg);
+
+ return 0;
+}
+
+static int emc_set_rate_and_parent(struct clk_hw *hw,
+ unsigned long rate,
+ unsigned long parent_rate,
+ u8 index)
+{
+ struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+ u32 val, div;
+
+ div = div_frac_get(rate, parent_rate, 8, 1, 0);
+
+ val = readl_relaxed(emc->reg);
+
+ val &= ~CLK_SOURCE_EMC_2X_CLK_SRC_MASK;
+ val |= index << CLK_SOURCE_EMC_2X_CLK_SRC_SHIFT;
+
+ val &= ~CLK_SOURCE_EMC_2X_CLK_DIVISOR_MASK;
+ val |= div;
+
+ if (index == EMC_SRC_PLL_M && div == 0 && emc->want_low_jitter)
+ val |= USE_PLLM_UD;
+ else
+ val &= ~USE_PLLM_UD;
+
+ if (emc->mc_same_freq)
+ val |= MC_EMC_SAME_FREQ;
+ else
+ val &= ~MC_EMC_SAME_FREQ;
+
+ writel_relaxed(val, emc->reg);
+
+ fence_udelay(1, emc->reg);
+
+ return 0;
+}
+
+static int emc_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
+{
+ struct tegra_clk_emc *emc = to_tegra_clk_emc(hw);
+ struct clk_hw *parent_hw;
+ unsigned long divided_rate;
+ unsigned long parent_rate;
+ unsigned int i;
+ long emc_rate;
+ int div;
+
+ emc_rate = emc->round_cb(req->rate, req->min_rate, req->max_rate,
+ emc->cb_arg);
+ if (emc_rate < 0)
+ return emc_rate;
+
+ for (i = 0; i < ARRAY_SIZE(emc_parent_clk_names); i++) {
+ parent_hw = clk_hw_get_parent_by_index(hw, i);
+
+ if (req->best_parent_hw == parent_hw)
+ parent_rate = req->best_parent_rate;
+ else
+ parent_rate = clk_hw_get_rate(parent_hw);
+
+ if (emc_rate > parent_rate)
+ continue;
+
+ div = div_frac_get(emc_rate, parent_rate, 8, 1, 0);
+ divided_rate = DIV_ROUND_UP(parent_rate * 2, div + 2);
+
+ if (divided_rate != emc_rate)
+ continue;
+
+ req->best_parent_rate = parent_rate;
+ req->best_parent_hw = parent_hw;
+ req->rate = emc_rate;
+ break;
+ }
+
+ if (i == ARRAY_SIZE(emc_parent_clk_names)) {
+ pr_err_once("can't find parent for rate %lu emc_rate %lu\n",
+ req->rate, emc_rate);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static const struct clk_ops tegra_clk_emc_ops = {
+ .recalc_rate = emc_recalc_rate,
+ .get_parent = emc_get_parent,
+ .set_parent = emc_set_parent,
+ .set_rate = emc_set_rate,
+ .set_rate_and_parent = emc_set_rate_and_parent,
+ .determine_rate = emc_determine_rate,
+};
+
+void tegra20_clk_set_emc_round_callback(tegra20_clk_emc_round_cb *round_cb,
+ void *cb_arg)
+{
+ struct clk *clk = __clk_lookup("emc");
+ struct tegra_clk_emc *emc;
+ struct clk_hw *hw;
+
+ if (clk) {
+ hw = __clk_get_hw(clk);
+ emc = to_tegra_clk_emc(hw);
+
+ emc->round_cb = round_cb;
+ emc->cb_arg = cb_arg;
+ }
+}
+
+bool tegra20_clk_emc_driver_available(struct clk_hw *emc_hw)
+{
+ return to_tegra_clk_emc(emc_hw)->round_cb != NULL;
+}
+
+struct clk *tegra20_clk_register_emc(void __iomem *ioaddr, bool low_jitter)
+{
+ struct tegra_clk_emc *emc;
+ struct clk_init_data init;
+ struct clk *clk;
+
+ emc = kzalloc(sizeof(*emc), GFP_KERNEL);
+ if (!emc)
+ return NULL;
+
+ /*
+ * EMC stands for External Memory Controller.
+ *
+ * We don't want EMC clock to be disabled ever by gating its
+ * parent and whatnot because system is busted immediately in that
+ * case, hence the clock is marked as critical.
+ */
+ init.name = "emc";
+ init.ops = &tegra_clk_emc_ops;
+ init.flags = CLK_IS_CRITICAL;
+ init.parent_names = emc_parent_clk_names;
+ init.num_parents = ARRAY_SIZE(emc_parent_clk_names);
+
+ emc->reg = ioaddr;
+ emc->hw.init = &init;
+ emc->want_low_jitter = low_jitter;
+
+ clk = clk_register(NULL, &emc->hw);
+ if (IS_ERR(clk)) {
+ kfree(emc);
+ return NULL;
+ }
+
+ return clk;
+}
+
+int tegra20_clk_prepare_emc_mc_same_freq(struct clk *emc_clk, bool same)
+{
+ struct tegra_clk_emc *emc;
+ struct clk_hw *hw;
+
+ if (!emc_clk)
+ return -EINVAL;
+
+ hw = __clk_get_hw(emc_clk);
+ emc = to_tegra_clk_emc(hw);
+ emc->mc_same_freq = same;
+
+ return 0;
+}
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