On Thursday 31 March 2016 10:38 PM, Jose Abreu wrote:
> The ARC SDP I2S clock can be programmed using a
> specific PLL.
>
> This patch has the goal of adding a clock driver
> that programs this PLL.
>
> At this moment the rate values are hardcoded in
> a table but in the future it would be ideal to
> use a function which determines the PLL values
> given the desired rate.
>
> Signed-off-by: Jose Abreu <joabreu at synopsys.com>
> ---
>
> Changes v2 -> v3:
> * Implemented recalc_rate
>
> Changes v1 -> v2:
> * Renamed folder to axs10x (as suggested by Alexey Brodkin)
> * Added more supported rates
>
> arch/arc/boot/dts/axs10x_mb.dtsi | 5 ++
> drivers/clk/Makefile | 1 +
> drivers/clk/axs10x/Makefile | 1 +
> drivers/clk/axs10x/i2s_pll_clock.c | 163 +++++++++++++++++++++++++++++++++++++
> 4 files changed, 170 insertions(+)
> create mode 100644 drivers/clk/axs10x/Makefile
> create mode 100644 drivers/clk/axs10x/i2s_pll_clock.c
>
> diff --git a/arch/arc/boot/dts/axs10x_mb.dtsi b/arch/arc/boot/dts/axs10x_mb.dtsi
> index ab5d570..9c68226 100644
> --- a/arch/arc/boot/dts/axs10x_mb.dtsi
> +++ b/arch/arc/boot/dts/axs10x_mb.dtsi
> @@ -23,6 +23,11 @@
> #clock-cells = <0>;
> };
>
> + i2sclk: i2sclk {
> + compatible = "snps,i2s-pll-clock";
> + #clock-cells = <0>;
> + };
> +
> apbclk: apbclk {
> compatible = "fixed-clock";
> clock-frequency = <50000000>;
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 46869d6..2ca62dc6 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -84,3 +84,4 @@ obj-$(CONFIG_X86) += x86/
> obj-$(CONFIG_ARCH_ZX) += zte/
> obj-$(CONFIG_ARCH_ZYNQ) += zynq/
> obj-$(CONFIG_H8300) += h8300/
> +obj-$(CONFIG_ARC_PLAT_AXS10X) += axs10x/
> diff --git a/drivers/clk/axs10x/Makefile b/drivers/clk/axs10x/Makefile
> new file mode 100644
> index 0000000..01996b8
> --- /dev/null
> +++ b/drivers/clk/axs10x/Makefile
> @@ -0,0 +1 @@
> +obj-y += i2s_pll_clock.o
> diff --git a/drivers/clk/axs10x/i2s_pll_clock.c b/drivers/clk/axs10x/i2s_pll_clock.c
> new file mode 100644
> index 0000000..f050e70
> --- /dev/null
> +++ b/drivers/clk/axs10x/i2s_pll_clock.c
> @@ -0,0 +1,163 @@
> +/*
> + * Synopsys AXS10X SDP I2S PLL clock driver
> + *
> + * Copyright (C) 2016 Synopsys
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/device.h>
> +#include <linux/of_address.h>
> +#include <linux/slab.h>
> +
> +/* FPGA Version Info */
> +#define FPGA_VER_INFO 0xE0011230
> +#define FPGA_VER_27M 0x000FBED9
> +
> +/* PLL registers addresses */
> +#define PLL_IDIV_ADDR 0xE00100A0
> +#define PLL_FBDIV_ADDR 0xE00100A4
> +#define PLL_ODIV0_ADDR 0xE00100A8
> +#define PLL_ODIV1_ADDR 0xE00100AC
> +
> +struct i2s_pll_cfg {
> + unsigned int rate;
> + unsigned int idiv;
> + unsigned int fbdiv;
> + unsigned int odiv0;
> + unsigned int odiv1;
> +};
> +
> +static struct i2s_pll_cfg i2s_pll_cfg_27m[] = {
> + /* 27 Mhz */
> + { 1024000, 0x104, 0x451, 0x10E38, 0x2000 },
> + { 1411200, 0x104, 0x596, 0x10D35, 0x2000 },
> + { 1536000, 0x208, 0xA28, 0x10B2C, 0x2000 },
> + { 2048000, 0x82, 0x451, 0x10E38, 0x2000 },
> + { 2822400, 0x82, 0x596, 0x10D35, 0x2000 },
> + { 3072000, 0x104, 0xA28, 0x10B2C, 0x2000 },
> + { 2116800, 0x82, 0x3CF, 0x10C30, 0x2000 },
> + { 2304000, 0x104, 0x79E, 0x10B2C, 0x2000 },
> + { 0, 0, 0, 0, 0 },
> +};
> +
> +static struct i2s_pll_cfg i2s_pll_cfg_28m[] = {
> + /* 28.224 Mhz */
> + { 1024000, 0x82, 0x105, 0x107DF, 0x2000 },
> + { 1411200, 0x28A, 0x1, 0x10001, 0x2000 },
> + { 1536000, 0xA28, 0x187, 0x10042, 0x2000 },
> + { 2048000, 0x41, 0x105, 0x107DF, 0x2000 },
> + { 2822400, 0x145, 0x1, 0x10001, 0x2000 },
> + { 3072000, 0x514, 0x187, 0x10042, 0x2000 },
> + { 2116800, 0x514, 0x42, 0x10001, 0x2000 },
> + { 2304000, 0x619, 0x82, 0x10001, 0x2000 },
> + { 0, 0, 0, 0, 0 },
> +};
> +
> +struct i2s_pll_clk {
> + struct clk_hw hw;
> + unsigned long ref_clk;
> + struct i2s_pll_cfg *pll_cfg;
> +};
> +
> +static inline struct i2s_pll_clk *to_i2s_pll_clk(struct clk_hw *hw)
> +{
> + return container_of(hw, struct i2s_pll_clk, hw);
> +}
Abstraction is good, but do you really need this. I mean do you foresee future
changes where this implementation might change.
> +
> +static unsigned int i2s_pll_get_value(unsigned int val)
> +{
> + return ((val & 0x3F) + ((val >> 6) & 0x3F));
> +}
> +
> +static unsigned long i2s_pll_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct i2s_pll_clk *clk = to_i2s_pll_clk(hw);
> + unsigned int idiv, fbdiv, odiv;
> +
> + idiv = i2s_pll_get_value(readl((void *)PLL_IDIV_ADDR));
> + fbdiv = i2s_pll_get_value(readl((void *)PLL_FBDIV_ADDR));
> + odiv = i2s_pll_get_value(readl((void *)PLL_ODIV0_ADDR));
See comment below - you can probably use readl_relaxed()
> +
> + return (((clk->ref_clk / idiv ) * fbdiv) / odiv);
> +}
> +
> +static long i2s_pll_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *prate)
> +{
> + /* TODO: Round rate to nearest valid rate */
> + return rate;
> +}
> +
> +static int i2s_pll_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct i2s_pll_cfg *pll_cfg = to_i2s_pll_clk(hw)->pll_cfg;
> + int i;
> +
> + for (i = 0; pll_cfg[i].rate != 0; i++) {
> + if (pll_cfg[i].rate == rate) {
> + writel(pll_cfg[i].idiv, (void *)PLL_IDIV_ADDR);
> + writel(pll_cfg[i].fbdiv, (void *)PLL_FBDIV_ADDR);
> + writel(pll_cfg[i].odiv0, (void *)PLL_ODIV0_ADDR);
> + writel(pll_cfg[i].odiv1, (void *)PLL_ODIV1_ADDR);
Note that there are writel_relaxed and readl_relaxed io accessors, which generate
better code, specially on ARC. If there is no strict ordering requirement for the
various PLL regs, you are safely use them.
> + return 0;
> + }
> + }
> +
> + pr_err("%s: invalid rate=%ld, parent_rate=%ld\n", __func__,
> + rate, parent_rate);
> + return -EINVAL;
> +}
> +
> +static const struct clk_ops i2s_pll_ops = {
> + .recalc_rate = i2s_pll_recalc_rate,
> + .round_rate = i2s_pll_round_rate,
> + .set_rate = i2s_pll_set_rate,
> +};
> +
> +static void __init i2s_pll_clk_setup(struct device_node *node)
> +{
> + const char *clk_name = node->name;
> + struct clk *clk;
> + struct i2s_pll_clk *pll_clk;
> + struct clk_init_data init;
> +
> + pll_clk = kzalloc(sizeof(*pll_clk), GFP_KERNEL);
> + if (!pll_clk)
> + return;
> +
> + init.name = clk_name;
> + init.ops = &i2s_pll_ops;
> + init.flags = CLK_IS_BASIC;
> + init.num_parents = 0;
> + pll_clk->hw.init = &init;
> +
> + clk = clk_register(NULL, &pll_clk->hw);
> + if (IS_ERR(clk)) {
> + pr_err("%s: failed to register %s div clock (%ld)\n",
> + __func__, clk_name, PTR_ERR(clk));
> + goto free_clock;
> + }
> +
> + if (readl((void *)FPGA_VER_INFO) <= FPGA_VER_27M) {
readl_relaxed ?
> + pll_clk->ref_clk = 27000000;
> + pll_clk->pll_cfg = i2s_pll_cfg_27m;
> + } else {
> + pll_clk->ref_clk = 28224000;
> + pll_clk->pll_cfg = i2s_pll_cfg_28m;
> + }
> +
> + of_clk_add_provider(node, of_clk_src_simple_get, clk);
> + return;
> +
> +free_clock:
> + kfree(pll_clk);
> +}
> +
> +CLK_OF_DECLARE(i2s_pll_clk, "snps,i2s-pll-clock", i2s_pll_clk_setup);
> +
>
