[PATCH v4 01/10] clk: tegra20/30: Add custom EMC clock implementation

Dmitry Osipenko
2019-06-16T23:35:42Z

A proper External Memory Controller clock rounding and parent selection
functionality is required by the EMC drivers. It is not available using
the generic clock implementation, hence add a custom one. The clock rate
rounding shall be done by the EMC drivers because they have information
about available memory timings, so the drivers will have to register a
callback that will round the requested rate. EMC clock users won't be able
to request EMC clock by getting -EPROBE_DEFER until EMC driver is probed
and the callback is set up. The functionality is somewhat similar to the
clk-emc.c which serves Tegra124+ SoC's, the later HW generations support
more parent clock sources and the HW configuration and integration with
the EMC drivers differs a tad from the older gens, hence it's not really
worth to try to squash everything into a single source file.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
drivers/clk/tegra/Makefile | 2 +
drivers/clk/tegra/clk-tegra20-emc.c | 305 ++++++++++++++++++++++++++++
drivers/clk/tegra/clk-tegra20.c | 55 ++---
drivers/clk/tegra/clk-tegra30.c | 38 +++-
drivers/clk/tegra/clk.h | 6 +
include/linux/clk/tegra.h | 14 ++
6 files changed, 368 insertions(+), 52 deletions(-)
create mode 100644 drivers/clk/tegra/clk-tegra20-emc.c

diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
index 4812e45c2214..df966ca06788 100644
--- a/drivers/clk/tegra/Makefile
+++ b/drivers/clk/tegra/Makefile
@@ -17,7 +17,9 @@ obj-y += clk-tegra-fixed.o
obj-y += clk-tegra-super-gen4.o
obj-$(CONFIG_TEGRA_CLK_EMC) += clk-emc.o
obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += clk-tegra20.o
+obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += clk-tegra20-emc.o
obj-$(CONFIG_ARCH_TEGRA_3x_SOC) += clk-tegra30.o
+obj-$(CONFIG_ARCH_TEGRA_3x_SOC) += clk-tegra20-emc.o
obj-$(CONFIG_ARCH_TEGRA_114_SOC) += clk-tegra114.o
obj-$(CONFIG_ARCH_TEGRA_124_SOC) += clk-tegra124.o
obj-$(CONFIG_TEGRA_CLK_DFLL) += clk-tegra124-dfll-fcpu.o
diff --git a/drivers/clk/tegra/clk-tegra20-emc.c b/drivers/clk/tegra/clk-tegra20-emc.c
new file mode 100644
index 000000000000..b7f64ad5c04c
--- /dev/null
+++ b/drivers/clk/tegra/clk-tegra20-emc.c
@@ -0,0 +1,305 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#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("%s: can't find parent for rate %lu emc_rate %lu\n",
+ __func__, 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)
+{
+ struct tegra_clk_emc *emc;
+ struct clk_init_data init;
+ struct clk *clk;
+
+ emc = kzalloc(sizeof(*emc), GFP_KERNEL);
+ if (!emc)
+ return NULL;
+
+ 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;
+
+ clk = clk_register(NULL, &emc->hw);
+ if (IS_ERR(clk)) {
+ kfree(emc);
+ return NULL;
+ }
+
+ return clk;
+}
+
+void tegra30_clk_set_emc_round_callback(tegra30_clk_emc_round_cb *round_cb,
+ void *cb_arg)
+{
+ tegra20_clk_set_emc_round_callback(round_cb, cb_arg);
+}
+
+bool tegra30_clk_emc_driver_available(struct clk_hw *emc_hw)
+{
+ return tegra20_clk_emc_driver_available(emc_hw);
+}
+
+struct clk *tegra30_clk_register_emc(void __iomem *ioaddr)
+{
+ struct tegra_clk_emc *emc;
+ struct clk_hw *hw;
+ struct clk *clk;
+
+ clk = tegra20_clk_register_emc(ioaddr);
+ if (!clk)
+ return NULL;
+
+ hw = __clk_get_hw(clk);
+ emc = to_tegra_clk_emc(hw);
+ emc->want_low_jitter = true;
+
+ return clk;
+}
+
+int tegra30_clk_prepare_emc_mc_same_freq(struct clk *emc_clk, bool same)
+{
+ struct tegra_clk_emc *emc;
+ struct clk_hw *hw;
+
+ if (emc_clk) {
+ hw = __clk_get_hw(emc_clk);
+ emc = to_tegra_clk_emc(hw);
+ emc->mc_same_freq = same;
+
+ return 0;
+ }
+
+ return -EINVAL;
+}
diff --git a/drivers/clk/tegra/clk-tegra20.c b/drivers/clk/tegra/clk-tegra20.c
index bcd871134f45..f937a0f35afb 100644
--- a/drivers/clk/tegra/clk-tegra20.c
+++ b/drivers/clk/tegra/clk-tegra20.c
@@ -130,8 +130,6 @@ static struct cpu_clk_suspend_context {
static void __iomem *clk_base;
static void __iomem *pmc_base;

-static DEFINE_SPINLOCK(emc_lock);
-
#define TEGRA_INIT_DATA_MUX(_name, _parents, _offset, \
_clk_num, _gate_flags, _clk_id) \
TEGRA_INIT_DATA(_name, NULL, NULL, _parents, _offset, \
@@ -760,7 +758,6 @@ static const char *pwm_parents[] = { "pll_p", "pll_c", "audio", "clk_m",
static const char *mux_pllpcm_clkm[] = { "pll_p", "pll_c", "pll_m", "clk_m" };
static const char *mux_pllpdc_clkm[] = { "pll_p", "pll_d_out0", "pll_c",
"clk_m" };
-static const char *mux_pllmcp_clkm[] = { "pll_m", "pll_c", "pll_p", "clk_m" };

static struct tegra_periph_init_data tegra_periph_clk_list[] = {
TEGRA_INIT_DATA_MUX("i2s1", i2s1_parents, CLK_SOURCE_I2S1, 11, TEGRA_PERIPH_ON_APB, TEGRA20_CLK_I2S1),
@@ -787,41 +784,6 @@ static struct tegra_periph_init_data tegra_periph_nodiv_clk_list[] = {
TEGRA_INIT_DATA_NODIV("disp2", mux_pllpdc_clkm, CLK_SOURCE_DISP2, 30, 2, 26, 0, TEGRA20_CLK_DISP2),
};

-static void __init tegra20_emc_clk_init(void)
-{
- const u32 use_pllm_ud = BIT(29);
- struct clk *clk;
- u32 emc_reg;
-
- clk = clk_register_mux(NULL, "emc_mux", mux_pllmcp_clkm,
- ARRAY_SIZE(mux_pllmcp_clkm),
- CLK_SET_RATE_NO_REPARENT,
- clk_base + CLK_SOURCE_EMC,
- 30, 2, 0, &emc_lock);
-
- clk = tegra_clk_register_mc("mc", "emc_mux", clk_base + CLK_SOURCE_EMC,
- &emc_lock);
- clks[TEGRA20_CLK_MC] = clk;
-
- /* un-divided pll_m_out0 is currently unsupported */
- emc_reg = readl_relaxed(clk_base + CLK_SOURCE_EMC);
- if (emc_reg & use_pllm_ud) {
- pr_err("%s: un-divided PllM_out0 used as clock source\n",
- __func__);
- return;
- }
-
- /*
- * Note that 'emc_mux' source and 'emc' rate shouldn't be changed at
- * the same time due to a HW bug, this won't happen because we're
- * defining 'emc_mux' and 'emc' as distinct clocks.
- */
- clk = tegra_clk_register_divider("emc", "emc_mux",
- clk_base + CLK_SOURCE_EMC, CLK_IS_CRITICAL,
- TEGRA_DIVIDER_INT, 0, 8, 1, &emc_lock);
- clks[TEGRA20_CLK_EMC] = clk;
-}
-
static void __init tegra20_periph_clk_init(void)
{
struct tegra_periph_init_data *data;
@@ -835,7 +797,13 @@ static void __init tegra20_periph_clk_init(void)
clks[TEGRA20_CLK_AC97] = clk;

/* emc */
- tegra20_emc_clk_init();
+ clk = tegra20_clk_register_emc(clk_base + CLK_SOURCE_EMC);
+
+ clks[TEGRA20_CLK_EMC] = clk;
+
+ clk = tegra_clk_register_mc("mc", "emc", clk_base + CLK_SOURCE_EMC,
+ NULL);
+ clks[TEGRA20_CLK_MC] = clk;

/* dsi */
clk = tegra_clk_register_periph_gate("dsi", "pll_d", 0, clk_base, 0,
@@ -1115,6 +1083,8 @@ static struct clk *tegra20_clk_src_onecell_get(struct of_phandle_args *clkspec,
if (IS_ERR(clk))
return clk;

+ hw = __clk_get_hw(clk);
+
/*
* Tegra20 CDEV1 and CDEV2 clocks are a bit special case, their parent
* clock is created by the pinctrl driver. It is possible for clk user
@@ -1124,13 +1094,16 @@ static struct clk *tegra20_clk_src_onecell_get(struct of_phandle_args *clkspec,
*/
if (clkspec->args[0] == TEGRA20_CLK_CDEV1 ||
clkspec->args[0] == TEGRA20_CLK_CDEV2) {
- hw = __clk_get_hw(clk);
-
parent_hw = clk_hw_get_parent(hw);
if (!parent_hw)
return ERR_PTR(-EPROBE_DEFER);
}

+ if (clkspec->args[0] == TEGRA20_CLK_EMC) {
+ if (!tegra20_clk_emc_driver_available(hw))
+ return ERR_PTR(-EPROBE_DEFER);
+ }
+
return clk;
}

diff --git a/drivers/clk/tegra/clk-tegra30.c b/drivers/clk/tegra/clk-tegra30.c
index 7b4c6a488527..fab075808c20 100644
--- a/drivers/clk/tegra/clk-tegra30.c
+++ b/drivers/clk/tegra/clk-tegra30.c
@@ -151,7 +151,6 @@ static unsigned long input_freq;

static DEFINE_SPINLOCK(cml_lock);
static DEFINE_SPINLOCK(pll_d_lock);
-static DEFINE_SPINLOCK(emc_lock);

#define TEGRA_INIT_DATA_MUX(_name, _parents, _offset, \
_clk_num, _gate_flags, _clk_id) \
@@ -808,7 +807,7 @@ static struct tegra_clk tegra30_clks[tegra_clk_max] __initdata = {
[tegra_clk_pll_a] = { .dt_id = TEGRA30_CLK_PLL_A, .present = true },
[tegra_clk_pll_a_out0] = { .dt_id = TEGRA30_CLK_PLL_A_OUT0, .present = true },
[tegra_clk_cec] = { .dt_id = TEGRA30_CLK_CEC, .present = true },
- [tegra_clk_emc] = { .dt_id = TEGRA30_CLK_EMC, .present = true },
+ [tegra_clk_emc] = { .dt_id = TEGRA30_CLK_EMC, .present = false },
};

static const char *pll_e_parents[] = { "pll_ref", "pll_p" };
@@ -995,7 +994,6 @@ static void __init tegra30_super_clk_init(void)
static const char *mux_pllacp_clkm[] = { "pll_a_out0", "unused", "pll_p",
"clk_m" };
static const char *mux_pllpcm_clkm[] = { "pll_p", "pll_c", "pll_m", "clk_m" };
-static const char *mux_pllmcp_clkm[] = { "pll_m", "pll_c", "pll_p", "clk_m" };
static const char *spdif_out_parents[] = { "pll_a_out0", "spdif_2x", "pll_p",
"clk_m" };
static const char *mux_pllmcpa[] = { "pll_m", "pll_c", "pll_p", "pll_a_out0" };
@@ -1044,14 +1042,12 @@ static void __init tegra30_periph_clk_init(void)
clks[TEGRA30_CLK_AFI] = clk;

/* emc */
- clk = clk_register_mux(NULL, "emc_mux", mux_pllmcp_clkm,
- ARRAY_SIZE(mux_pllmcp_clkm),
- CLK_SET_RATE_NO_REPARENT,
- clk_base + CLK_SOURCE_EMC,
- 30, 2, 0, &emc_lock);
+ clk = tegra30_clk_register_emc(clk_base + CLK_SOURCE_EMC);
+
+ clks[TEGRA30_CLK_EMC] = clk;

- clk = tegra_clk_register_mc("mc", "emc_mux", clk_base + CLK_SOURCE_EMC,
- &emc_lock);
+ clk = tegra_clk_register_mc("mc", "emc", clk_base + CLK_SOURCE_EMC,
+ NULL);
clks[TEGRA30_CLK_MC] = clk;

/* cml0 */
@@ -1302,6 +1298,26 @@ static struct tegra_audio_clk_info tegra30_audio_plls[] = {
{ "pll_a", &pll_a_params, tegra_clk_pll_a, "pll_p_out1" },
};

+static struct clk *tegra30_clk_src_onecell_get(struct of_phandle_args *clkspec,
+ void *data)
+{
+ struct clk_hw *hw;
+ struct clk *clk;
+
+ clk = of_clk_src_onecell_get(clkspec, data);
+ if (IS_ERR(clk))
+ return clk;
+
+ hw = __clk_get_hw(clk);
+
+ if (clkspec->args[0] == TEGRA30_CLK_EMC) {
+ if (!tegra30_clk_emc_driver_available(hw))
+ return ERR_PTR(-EPROBE_DEFER);
+ }
+
+ return clk;
+}
+
static void __init tegra30_clock_init(struct device_node *np)
{
struct device_node *node;
@@ -1345,7 +1361,7 @@ static void __init tegra30_clock_init(struct device_node *np)

tegra_init_dup_clks(tegra_clk_duplicates, clks, TEGRA30_CLK_CLK_MAX);

- tegra_add_of_provider(np, of_clk_src_onecell_get);
+ tegra_add_of_provider(np, tegra30_clk_src_onecell_get);
tegra_register_devclks(devclks, ARRAY_SIZE(devclks));

tegra_clk_apply_init_table = tegra30_clock_apply_init_table;
diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index 905bf1096558..1eb2ec20e343 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -838,4 +838,10 @@ int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
udelay(delay); \
} while (0)

+bool tegra20_clk_emc_driver_available(struct clk_hw *emc_hw);
+struct clk *tegra20_clk_register_emc(void __iomem *ioaddr);
+
+bool tegra30_clk_emc_driver_available(struct clk_hw *emc_hw);
+struct clk *tegra30_clk_register_emc(void __iomem *ioaddr);
+
#endif /* TEGRA_CLK_H */
diff --git a/include/linux/clk/tegra.h b/include/linux/clk/tegra.h
index b8aef62cc3f5..8546e28aa518 100644
--- a/include/linux/clk/tegra.h
+++ b/include/linux/clk/tegra.h
@@ -119,4 +119,18 @@ extern void tegra210_put_utmipll_in_iddq(void);
extern void tegra210_put_utmipll_out_iddq(void);
extern int tegra210_clk_handle_mbist_war(unsigned int id);

+struct clk;
+
+typedef long (tegra20_clk_emc_round_cb)(unsigned long rate,
+ unsigned long min_rate,
+ unsigned long max_rate,
+ void *arg);
+#define tegra30_clk_emc_round_cb tegra20_clk_emc_round_cb
+
+void tegra20_clk_set_emc_round_callback(tegra20_clk_emc_round_cb *round_cb,
+ void *cb_arg);
+void tegra30_clk_set_emc_round_callback(tegra30_clk_emc_round_cb *round_cb,
+ void *cb_arg);
+int tegra30_clk_prepare_emc_mc_same_freq(struct clk *emc_clk, bool same);
+
#endif /* __LINUX_CLK_TEGRA_H_ */
--
2.22.0