clk: tegra: implement a reset driver

The Tegra CAR module implements both a clock and reset controller. So
far, the driver exposes the clock feature via the common clock API and
the reset feature using a custom API. This patch adds an implementation
of the common reset framework API (include/linux/reset*.h). The legacy
reset implementation will be removed once all drivers have been
converted.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Acked-By: Peter De Schrijver <pdeschrijver@nvidia.com>

drivers/clk/tegra/clk-tegra114.c

@@ -1460,7 +1460,8 @@ static void __init tegra114_clock_init(struct device_node *np)
 		return;
 	}
 
-	clks = tegra_clk_init(TEGRA114_CLK_CLK_MAX, TEGRA114_CLK_PERIPH_BANKS);
+	clks = tegra_clk_init(clk_base, TEGRA114_CLK_CLK_MAX,
+				TEGRA114_CLK_PERIPH_BANKS);
 	if (!clks)
 		return;
 

drivers/clk/tegra/clk-tegra124.c

@@ -1398,7 +1398,7 @@ static void __init tegra124_clock_init(struct device_node *np)
 		return;
 	}
 
-	clks = tegra_clk_init(TEGRA124_CLK_CLK_MAX, 6);
+	clks = tegra_clk_init(clk_base, TEGRA124_CLK_CLK_MAX, 6);
 	if (!clks)
 		return;
 

drivers/clk/tegra/clk-tegra20.c

@@ -1109,7 +1109,8 @@ static void __init tegra20_clock_init(struct device_node *np)
 		BUG();
 	}
 
-	clks = tegra_clk_init(TEGRA20_CLK_CLK_MAX, TEGRA20_CLK_PERIPH_BANKS);
+	clks = tegra_clk_init(clk_base, TEGRA20_CLK_CLK_MAX,
+				TEGRA20_CLK_PERIPH_BANKS);
 	if (!clks)
 		return;
 

drivers/clk/tegra/clk-tegra30.c

@@ -1427,7 +1427,8 @@ static void __init tegra30_clock_init(struct device_node *np)
 		BUG();
 	}
 
-	clks = tegra_clk_init(TEGRA30_CLK_CLK_MAX, TEGRA30_CLK_PERIPH_BANKS);
+	clks = tegra_clk_init(clk_base, TEGRA30_CLK_CLK_MAX,
+				TEGRA30_CLK_PERIPH_BANKS);
 	if (!clks)
 		return;
 

drivers/clk/tegra/clk.c

@@ -18,6 +18,8 @@
 #include <linux/clk-provider.h>
 #include <linux/of.h>
 #include <linux/clk/tegra.h>
+#include <linux/reset-controller.h>
+#include <linux/tegra-soc.h>
 
 #include "clk.h"
 
@@ -121,6 +123,35 @@ static struct tegra_clk_periph_regs periph_regs[] = {
 	},
 };
 
+static void __iomem *clk_base;
+
+static int tegra_clk_rst_assert(struct reset_controller_dev *rcdev,
+		unsigned long id)
+{
+	/*
+	 * If peripheral is on the APB bus then we must read the APB bus to
+	 * flush the write operation in apb bus. This will avoid peripheral
+	 * access after disabling clock. Since the reset driver has no
+	 * knowledge of which reset IDs represent which devices, simply do
+	 * this all the time.
+	 */
+	tegra_read_chipid();
+
+	writel_relaxed(BIT(id % 32),
+			clk_base + periph_regs[id / 32].rst_set_reg);
+
+	return 0;
+}
+
+static int tegra_clk_rst_deassert(struct reset_controller_dev *rcdev,
+		unsigned long id)
+{
+	writel_relaxed(BIT(id % 32),
+			clk_base + periph_regs[id / 32].rst_clr_reg);
+
+	return 0;
+}
+
 struct tegra_clk_periph_regs *get_reg_bank(int clkid)
 {
 	int reg_bank = clkid / 32;
@@ -133,8 +164,10 @@ struct tegra_clk_periph_regs *get_reg_bank(int clkid)
 	}
 }
 
-struct clk ** __init tegra_clk_init(int num, int banks)
+struct clk ** __init tegra_clk_init(void __iomem *regs, int num, int banks)
 {
+	clk_base = regs;
+
 	if (WARN_ON(banks > ARRAY_SIZE(periph_regs)))
 		return NULL;
 
@@ -203,6 +236,17 @@ void __init tegra_init_from_table(struct tegra_clk_init_table *tbl,
 	}
 }
 
+static struct reset_control_ops rst_ops = {
+	.assert = tegra_clk_rst_assert,
+	.deassert = tegra_clk_rst_deassert,
+};
+
+static struct reset_controller_dev rst_ctlr = {
+	.ops = &rst_ops,
+	.owner = THIS_MODULE,
+	.of_reset_n_cells = 1,
+};
+
 void __init tegra_add_of_provider(struct device_node *np)
 {
 	int i;
@@ -220,6 +264,10 @@ void __init tegra_add_of_provider(struct device_node *np)
 	clk_data.clks = clks;
 	clk_data.clk_num = clk_num;
 	of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
+
+	rst_ctlr.of_node = np;
+	rst_ctlr.nr_resets = clk_num * 32;
+	reset_controller_register(&rst_ctlr);
 }
 
 void __init tegra_register_devclks(struct tegra_devclk *dev_clks, int num)

drivers/clk/tegra/clk.h

@@ -597,7 +597,7 @@ void tegra_init_dup_clks(struct tegra_clk_duplicate *dup_list,
 		struct clk *clks[], int clk_max);
 
 struct tegra_clk_periph_regs *get_reg_bank(int clkid);
-struct clk **tegra_clk_init(int num, int periph_banks);
+struct clk **tegra_clk_init(void __iomem *clk_base, int num, int periph_banks);
 
 struct clk **tegra_lookup_dt_id(int clk_id, struct tegra_clk *tegra_clk);