[PATCH V2 3/3] ARM: imx: source gpt per clk from OSC for system timer
From: festevam@gmail.com (Fabio Estevam)
Date: 2014-09-05 12:09:36
Also in:
linux-devicetree
On Fri, Sep 5, 2014 at 12:26 AM, Anson Huang [off-list ref] wrote:
On i.MX6Q TO > 1.0, i.MX6DL and i.MX6SX, gpt per clock
can be from OSC instead of ipg_per, as ipg_per's rate
may be scaled when system enter low bus mode, to keep
system timer NOT drift, better to make gpt per clock
at fixed rate, here add support for gpt per clock to
be from OSC which is at fixed rate always.
There are some difference on this implementation of
gpt per clock source, see below for details:
i.MX6Q TO > 1.0: GPT_CR_CLKSRC, 3b'101 selects fix clock
of OSC / 8 for gpt per clk;You mean "5b'101 selects fix clock..."
i.MX6DL and i.MX6SX: GPT_CR_CLKSRC, 3b'101 selects OSC
Same here: "5b'101"
quoted hunk
@@ -293,7 +299,7 @@ static int __init mxc_clockevent_init(struct clk *timer_clk) static void __init _mxc_timer_init(int irq, struct clk *clk_per, struct clk *clk_ipg) { - uint32_t tctl_val; + uint32_t tctl_val, tprer_val; if (IS_ERR(clk_per)) { pr_err("i.MX timer: unable to get clk\n");@@ -312,10 +318,26 @@ static void __init _mxc_timer_init(int irq, __raw_writel(0, timer_base + MXC_TCTL); __raw_writel(0, timer_base + MXC_TPRER); /* see datasheet note */ - if (timer_is_v2()) - tctl_val = V2_TCTL_CLK_PER | V2_TCTL_FRR | V2_TCTL_WAITEN | MXC_TCTL_TEN; - else + if (timer_is_v2()) { + if (((cpu_is_imx6q() && imx_get_soc_revision() > + IMX_CHIP_REVISION_1_0) || cpu_is_imx6dl() || + cpu_is_imx6sx()) && (clk_get_rate(clk_per) == + V2_TIMER_RATE_OSC_DIV8)) { + tctl_val = V2_TCTL_CLK_OSC_DIV8 | V2_TCTL_FRR | + V2_TCTL_WAITEN | MXC_TCTL_TEN; + if (cpu_is_imx6dl() || cpu_is_imx6sx()) { + /* 24 / 8 = 3 MHz */ + tprer_val = 7 << V2_TPRER_PRE24M; + __raw_writel(tprer_val, timer_base + MXC_TPRER); + tctl_val |= V2_TCTL_24MEN; + } + } else { + tctl_val = V2_TCTL_CLK_PER | V2_TCTL_FRR | + V2_TCTL_WAITEN | MXC_TCTL_TEN; + } + } else { tctl_val = MX1_2_TCTL_FRR | MX1_2_TCTL_CLK_PCLK1 | MXC_TCTL_TEN; + }
Can this block be rearranged a bit so that it becomes easier to read?